From jm_lekostaj at attglobal.net  Tue Nov  2 18:52:33 2004
From: jm_lekostaj at attglobal.net (Joe LeKostaj)
Date: Tue Nov  2 18:55:02 2004
Subject: [HBR] power transformer source
Message-ID: <p05010403bdadc988d3e7@[192.168.1.4]>

Hello. I'm posting this because it may be of interest to HBR 
constructors. There's a fellow on eHam.net selling power transformers 
that may be useful for HBR purposes. They're 115V input, 200-0-200V @ 
240 mA and 6.3V @ 6 amps.

http://www.eham.net/classifieds/detail/152933

He's got 75 pcs (!) to sell, and the price is right. I'm buying one 
thinking it should be usable for an HBR-11 if I forego using a tube 
rectifier. (There's no 5V winding for rectifier filament.) The 
rectified high voltage should go higher with the lighter load (90 mA) 
of the HBR-11 than the rated 240 mA load.

I'm not affiliated with the seller, nor do I guarantee the 
transformer will work as required for the HBR.  Am just passing along 
some info that others may find useful.

73,
Joe K9LY
From N2EY at aol.com  Tue Nov  2 19:39:55 2004
From: N2EY at aol.com (N2EY@aol.com)
Date: Tue Nov  2 19:42:53 2004
Subject: [HBR] power transformer source
Message-ID: <141.37e77400.2eb982db@aol.com>

In a message dated 11/2/04 6:55:39 PM Eastern Standard Time, 
jm_lekostaj@attglobal.net writes:


> They're 115V input, 200-0-200V @ 
> 240 mA and 6.3V @ 6 amps.
> 

let's see...

with silicon full-wave-centertap rectifier and a capacitor input filter, we 
can expect about 280 volts B+ at input to filter. (1.4 x 200) Allowing some 
drop in the chokes, a B+ of about 250 volts shouldn't be too hard to get.

with silicon "economy" supply (full wave bridge and center rectifier), 
capacitor only-filter on the high tap and capacitor input filter on the low, we can 
expect about 560 volts B+ on the high tap and about 260 on the low after the 
filter. Good for a MOPA up to almost 100 W.

73 de Jim, N2EY
From ljl160 at netzero.com  Wed Nov  3 21:56:11 2004
From: ljl160 at netzero.com (Lew)
Date: Fri Nov  5 16:58:43 2004
Subject: [HBR] coils
Message-ID: <008601c4c219$d8c6e1a0$e653fea9@optiplex>

Does anyone have a known working spare set of coils- preferably 40 meters that they might sell. I'm still trying to get my HBR16 percolating. I believe the main deficit is the coils  I got with it. Im not the original builder but I have most of the bugs out of it.  I can't get the 1st osc to run but everything else seems ok.  Thanks-Lew-K1NDV
From djmerz at 3-cities.com  Fri Nov  5 18:09:31 2004
From: djmerz at 3-cities.com (Dan Merz)
Date: Fri Nov  5 18:12:54 2004
Subject: [HBR] coils
References: <008601c4c219$d8c6e1a0$e653fea9@optiplex>
Message-ID: <000601c4c38c$86eea100$95c92d42@DansDell>

Lew,  I don't have spare coils but try a different oscillator tube if you've 
convinced yourself that the coil you have is wound ok and has the 
connections correct at the pins,  Dan
----- Original Message ----- 
From: "Lew" <ljl160@netzero.com>
To: <hbr@mailman.qth.net>
Sent: Wednesday, November 03, 2004 6:56 PM
Subject: [HBR] coils


Does anyone have a known working spare set of coils- preferably 40 meters 
that they might sell. I'm still trying to get my HBR16 percolating. I 
believe the main deficit is the coils  I got with it. Im not the original 
builder but I have most of the bugs out of it.  I can't get the 1st osc to 
run but everything else seems ok.  Thanks-Lew-K1NDV
************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and
construction notes...... via http://www.qsl.net/k5bcq/

Retrieve reflector archived data via 
http://mailman.qth.net/mailman/listinfo/hbr


From hbrnut at earthlink.net  Sat Nov  6 19:00:14 2004
From: hbrnut at earthlink.net (Darrell, WA5VGO)
Date: Sat Nov  6 19:03:37 2004
Subject: [HBR] (no subject)
Message-ID: <5.2.0.9.2.20041106175921.00bc6df8@mail.earthlink.net>

Lew,

Send me your complete set of 40 meter coils (Ant., mixer, osc.) and I'll 
put them in one of my HBR's and send them back to you peaked at 7.200kc. If 
they don't work, I should be able to get them working. I won't be able to 
adjust the tracking since that will vary from on set to another, but if I 
peak them in the middle of the band, they will definitely work in your 
receiver.

73,
Darrell, WA5VGO


At 09:56 PM 11/3/2004 -0500, you wrote:
Does anyone have a known working spare set of coils- preferably 40 meters 
that they might sell. I'm still trying to get my HBR16 percolating. I 
believe the main deficit is the coils  I got with it. Im not the original 
builder but I have most of the bugs out of it.  I can't get the 1st osc to 
run but everything else seems ok.  Thanks-Lew-K1NDV


From waltah at earthlink.net  Fri Nov 12 18:28:30 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Fri Nov 12 18:33:54 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 17
In-Reply-To: <4179920F.4534.FA4D9@localhost>
References: <416C14E8.20912.19C07F0@localhost>
Message-ID: <419500CE.16699.18B2A46@localhost>

"Good grief, Charlie Brown" edition ...

So after a few months of pretty hard work, I measured the 
interference-free dynamic range.  That's the range from the weakest 
signal you can copy to the strength of two strong equally spaced 
signals off to one side required to produce a same-frequency signal 
of strength equal to the one you're copying.   On the lower bands --
80 and 40 at least -- IFDR is often the determining factor in what 
you can copy and even more frequently determines when signals 
sound 'clean' and when they don't.   

 It was a rather disappointing 75 db.  Well above the early solid-
state rigs, on a par with the better Collins ham sets, not too close 
to the 90 db range of the R-390 and certainly not close to what I 
expected with a beam tube mixer and no RF stage.

I took stock.   The mixer is a 6JH8 operated at 140 volts on the 
plate; nearly all the published designs used 7360's.   Maybe that's 
a better tube, but the 6JH8 and 6ME8 came later; one wouldn't 
expect them to be markedly less good.   

The manufacturer's data sheets 'typical operation' info is 150 plate 
volts for the 7360 and 250 V for the 6JH8 and 6ME8 but I have seen 
comments that the 7360 requires 300 volts or so -- that's the 
manufacturers absolute maximum -- when used as a receiver 
mixer.  No doubt higher plate voltage would improve the linearity.  

I looked again for wiring errors and reconsidered test setup 
problems.   Didn't find any.  

(You can sniff out test setup problems by doing the testing at 
various signal levels.   Since this distortion follows a known law, 
IFDR can be calculated over a considerable range of input test 
signals and the calculated results should be in general agreement --
 say +/- a couple db, at worst.  If the receiver tests 'better' at low 
signal levels one suspects test signal leakage into the input 
circuits leading to a seemingly better figure for sensitivity or (less 
likely) cancellation of a signal produced by receiver non-linearity by 
a test setup problem; if 'worse' at low levels then the oscillators or 
hybrid combiner are at fault -- the oscillators may have excessive 
2nd harmonic distortion, they may crossmodulate each other, or 
the hybrid combiner may be overloaded.

I considered non-linearity of the coils in the receiver input circuits.   
I can't rule it out completely, but it doesn't seem too likely, either.   
The only practical way to reduce that while keeping this 
configuration is removing a turn from the antenna winding on the 
input coil to reduce the field strength in the coil.  But those cores 
are *large* (cup-and-core tunable part in series with a T50 toroid on 
40 and below); saturation at levels of ~ -13 dbm and less seems 
out of the question.   

A partial check on the location of the problem was to reduce the 
mixer cathode resistor.   I got more noise and less gain -- but the 
IFDR seemed to go up a couple db.  That seemed to finger the 
mixer.   

Fork in the road time.   75 db isn't that bad an IFDR and it can 
almost certainly be improved by raising the plate voltage to the 
maximum -- 250V for the 6JH8.   Increasing the plate voltage would 
require another transformer but it's certainly possible to do it.  But 
these tubes were supposed to be not just 'good', but outstanding in 
the linearity department.   Heck the R-390's get 90 db with 6C4 
mixers.   Why the hoop-la over beam tubes if it's a struggle to 
equal a 6C4?   Why not just duplicate the R-390 circuit with a far, 
far cheaper tube?   Might a 12AU7 with the halves in parallel be 
even better?   If we're doing that, what about a 5814?

Haven't I seen speculation about the properties of an 833A as a 
receiver RF stage?   

Such ideas certainly might be tried, but I still wanted to know why 
the big deal about beam tubes.   The only tube anybody used for 
the receiver mixer job was the 7360 and as it happened that was 
the only tube for which I had never printed a manufacturer's data 
sheet.   So I printed it.   Then I refilled the printer cartridge with ink 
and printed it again.

I think that was a light that just went on above my head.   RCA's 
data sheet shows two circuits using the 7360; one is a balanced 
modulator, the other is a high-level SSB mixer as would be used in 
a transmitter.   

Neither one of the two circuits was designed to give a rip about the 
linearity of reproduction of the signal on the tube's G1.   The 
balanced modulator used it for the carrier input, and the mixer, for 
conversion oscillator injection.   

The sign illuminated by that light bulb up there says "seen from 
G1, beam deflection tubes are just *pentodes*; there's no reason to 
expect remarkable linearity there.  What's highly linear is the path 
via the *deflection plate* input."

(From the curves in the tube data sheets the 7360 shows pretty 
good linearity over about 10V p-p on the deflection plates, while the 
6JH8 looks good to around 40V.)

In a receiver, acheivement of the remarkable performance of which 
these tubes are said to be capable seems to require driving one or 
both deflection grids with the antenna signal and using G1 for the 
local oscillator.   Since the single ended G1 signal is strongly 
rejected at the push-pull output that should have the added 
advantage of taking out most spurious responses, probably at the 
price of requiring a 9 Mcs trap in the antenna circuit.

There could even be instability problems, though it seems unlikely 
with the deflection plates having relatively low sensitivity and 
always tuned fairly well away from 9 Mcs.

I don't know about the deflection plate gain.   With input signals of 
10V on G1 and 8V on the deflection plates, RCA got 40V p-p on 
the ouput plates.  That's a conversion gain of >12db, but I probably 
can't put a 10V single-ended signal on G1 and the deflection plates 
draw a little bit of current -- maybe 10 uA for the 6JH8.   

However, unless the noise level is dramatically higher (why?) the 
sensitivity problem seemingly could be easily made up with an RF 
stage.  If the mixer input can truly reach levels of ~10V or more, 
there's room for lots of gain before there's a mixer overload issue.   
The 6EH7 is a great RF tube at these frequencies and running at 
very low gain should give an outstanding performance.

My first reaction was to cringe at the thought of rearranging the 
connections to that stage to reverse G1 and the deflection plates.   
Maybe a different tube would be better?  But it turns out that 
simply turning the 6JH8 socket 180 degrees will make it close 
enough.  The single ended premixer drive can be obtained with a 
link on the premixer plate coil.   The change shouldn't take over a 
day.   Well, that's not counting the (almost certainly needed) 
installation of an RF stage.   But at least I already have the socket 
hole center punched.

The remaining question is, if this speculation turns out to be right, 
why did everyone else get it wrong?   Such things happen -- there 
were whole decades in which we all told each other that good 
VFOs were wired with #8 wire.   But the reason for that error was 
simple -- we were looking at the excellent VFOs of WW-II which 
were expected to keep working in bombers with an engine shot 
away or ships providing shore fire at Omaha beach.  Taking the 
best VFOs of that period and simply rewiring them without all those 
internal struts (#8 wire is a pretty strong structural member) and 
heat pipes (#8 is pretty good at moving heat, too) would 
dramatically improve their performance under the more favorable 
conditions of our hamshack desks.

The gain's almost certainly higher with the input on G1 and when 
the HB-65, HB-67, Junior Miser's Dream, and the W1OMX designs 
were developed, nobody that I know of in the ham world was doing 
intermod testing, though obviously engineers like Ernie Pappenfus 
did it.   There were a couple of other QST articles in the 50s-60s 
timeframe by people who were aware of the issue, I believe -- By 
Goodman, right?   But weren't the designers of the SS-1R in the 
same league?  I don't know.

With a new tube type, there were no prexisting designs to follow.  
Once someone stuck the antenna signal in the logical place and 
got good results, why wouldn't others do the same?   All those 
designs were built in the last five years (1965-70, roughly) of the 
vacuum tube's ham radio lifespan; there wasn't the time for the 
hashing things over that occured with issues like VFO design, let 
alone linear amps.  

I'll know more in a couple of days.

Does anyone know of any receiver design using a 7360 (or other 
beam deflection tube) mixer with the input signal on the deflection 
plate(s)?

Walt 
KJ4KV


From N2EY at aol.com  Fri Nov 12 20:23:45 2004
From: N2EY at aol.com (N2EY@aol.com)
Date: Fri Nov 12 20:28:14 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 17
Message-ID: <190.32e1778b.2ec6bc21@aol.com>

In a message dated 11/12/2004 6:32:00 PM Eastern Standard Time, 
waltah@earthlink.net writes:


> So after a few months of pretty hard work, I measured the 
> interference-free dynamic range.  That's the range from the weakest 
> signal you can copy to the strength of two strong equally spaced 
> signals off to one side required to produce a same-frequency signal 
> of strength equal to the one you're copying.   On the lower bands --
> 80 and 40 at least -- IFDR is often the determining factor in what 
> you can copy and even more frequently determines when signals 
> sound 'clean' and when they don't.   
> 
> It was a rather disappointing 75 db.  Well above the early solid-
> state rigs, on a par with the better Collins ham sets, not too close 
> to the 90 db range of the R-390 and certainly not close to what I 
> expected with a beam tube mixer and no RF stage.
> 
> I took stock.   The mixer is a 6JH8 operated at 140 volts on the 
> plate; nearly all the published designs used 7360's.   Maybe that's 
> a better tube, but the 6JH8 and 6ME8 came later; one wouldn't 
> expect them to be markedly less good.   


All depends what they were intended to do. I don't think any of them were 
designed with the idea that they'd be rx mixers.

> 
> The manufacturer's data sheets 'typical operation' info is 150 plate 
> volts for the 7360 and 250 V for the 6JH8 and 6ME8 but I have seen 
> comments that the 7360 requires 300 volts or so -- that's the 
> manufacturers absolute maximum -- when used as a receiver 
> mixer.  No doubt higher plate voltage would improve the linearity.  
> 

In the Southgate Type 7, I use 250 volts on the 7360 mixer. W1KLK used 250 
volts too IIRC.


> I looked again for wiring errors and reconsidered test setup 
> problems.   Didn't find any.  
> 
> A partial check on the location of the problem was to reduce the 
> mixer cathode resistor.   I got more noise and less gain -- but the 
> IFDR seemed to go up a couple db.  That seemed to finger the 
> mixer.   
> 

Did you try different 6JH8s?


> Fork in the road time.   75 db isn't that bad an IFDR and it can 
> almost certainly be improved by raising the plate voltage to the 
> maximum -- 250V for the 6JH8.   Increasing the plate voltage would 
> require another transformer but it's certainly possible to do it.  But 
> these tubes were supposed to be not just 'good', but outstanding in 
> the linearity department.   Heck the R-390's get 90 db with 6C4 
> mixers.   Why the hoop-la over beam tubes if it's a struggle to 
> equal a 6C4?   Why not just duplicate the R-390 circuit with a far, 
> far cheaper tube?   Might a 12AU7 with the halves in parallel be 
> even better?   If we're doing that, what about a 5814?
> 
> Haven't I seen speculation about the properties of an 833A as a 
> receiver RF stage?   
> 

How about a 6ES8 Pullen mixer? 


> Such ideas certainly might be tried, but I still wanted to know why 
> the big deal about beam tubes.   The only tube anybody used for 
> the receiver mixer job was the 7360 and as it happened that was 
> the only tube for which I had never printed a manufacturer's data 
> sheet.   
> 
> I think that was a light that just went on above my head.   RCA's 
> data sheet shows two circuits using the 7360; one is a balanced 
> modulator, the other is a high-level SSB mixer as would be used in 
> a transmitter.   
> 
> Neither one of the two circuits was designed to give a rip about the 
> linearity of reproduction of the signal on the tube's G1.   The 
> balanced modulator used it for the carrier input, and the mixer, for 
> conversion oscillator injection.   
> 
> The sign illuminated by that light bulb up there says "seen from 
> G1, beam deflection tubes are just *pentodes*; there's no reason to 
> expect remarkable linearity there.  What's highly linear is the path 
> via the *deflection plate* input."
> 
> (From the curves in the tube data sheets the 7360 shows pretty 
> good linearity over about 10V p-p on the deflection plates, while the 
> 6JH8 looks good to around 40V.)
> 
> In a receiver, acheivement of the remarkable performance of which 
> these tubes are said to be capable seems to require driving one or 
> both deflection grids with the antenna signal and using G1 for the 
> local oscillator.   Since the single ended G1 signal is strongly 
> rejected at the push-pull output that should have the added 
> advantage of taking out most spurious responses, probably at the 
> price of requiring a 9 Mcs trap in the antenna circuit.
> 
> There could even be instability problems, though it seems unlikely 
> with the deflection plates having relatively low sensitivity and 
> always tuned fairly well away from 9 Mcs.
> 
> I don't know about the deflection plate gain.   With input signals of 
> 10V on G1 and 8V on the deflection plates, RCA got 40V p-p on 
> the ouput plates.  That's a conversion gain of >12db, but I probably 
> can't put a 10V single-ended signal on G1 and the deflection plates 
> draw a little bit of current -- maybe 10 uA for the 6JH8.   
> 
> However, unless the noise level is dramatically higher (why?) the 
> sensitivity problem seemingly could be easily made up with an RF 
> stage.  If the mixer input can truly reach levels of ~10V or more, 
> there's room for lots of gain before there's a mixer overload issue.   
> The 6EH7 is a great RF tube at these frequencies and running at 
> very low gain should give an outstanding performance.
> 
> My first reaction was to cringe at the thought of rearranging the 
> connections to that stage to reverse G1 and the deflection plates.   
> Maybe a different tube would be better?  But it turns out that 
> simply turning the 6JH8 socket 180 degrees will make it close 
> enough.  The single ended premixer drive can be obtained with a 
> link on the premixer plate coil.   The change shouldn't take over a 
> day.   Well, that's not counting the (almost certainly needed) 
> installation of an RF stage.   But at least I already have the socket 
> hole center punched.
> 
> The remaining question is, if this speculation turns out to be right, 
> why did everyone else get it wrong?   


But did they?

Squires-Sanders measured dynamic range differently. They set up the rx to 
receive a weak signal (say, 2uV) then saw how strong a signal they could park a 
few kHz away and still not desense. 

Such things happen -- there 
> 
> were whole decades in which we all told each other that good 
> VFOs were wired with #8 wire.   But the reason for that error was 
> simple -- we were looking at the excellent VFOs of WW-II which 
> were expected to keep working in bombers with an engine shot 
> away or ships providing shore fire at Omaha beach.  Taking the 
> best VFOs of that period and simply rewiring them without all those 
> internal struts (#8 wire is a pretty strong structural member) and 
> heat pipes (#8 is pretty good at moving heat, too) would 
> dramatically improve their performance under the more favorable 
> conditions of our hamshack desks.

Maybe! There's also the issue of mechanical stability.



> 
> The gain's almost certainly higher with the input on G1 and when 
> the HB-65, HB-67, Junior Miser's Dream, and the W1OMX designs 
> were developed, nobody that I know of in the ham world was doing 
> intermod testing, though obviously engineers like Ernie Pappenfus 
> did it.   There were a couple of other QST articles in the 50s-60s 
> timeframe by people who were aware of the issue, I believe -- By 
> Goodman, right?   But weren't the designers of the SS-1R in the 
> same league?  I don't know.

I think they were. But they may have used different standards of measurement.

There's also the RSGB work.

> 
> With a new tube type, there were no prexisting designs to follow.  
> Once someone stuck the antenna signal in the logical place and 
> got good results, why wouldn't others do the same?   All those 
> designs were built in the last five years (1965-70, roughly) of the 
> vacuum tube's ham radio lifespan; there wasn't the time for the 
> hashing things over that occured with issues like VFO design, let 
> alone linear amps.  

The SS-1R and MD came earlier - definitely before 1965.


> 
> I'll know more in a couple of days.
> 
> Does anyone know of any receiver design using a 7360 (or other 
> beam deflection tube) mixer with the input signal on the deflection 
> plate(s)?
> 


Never seen one.

Remember that RCA meant the 7360 for highlevel appications - they listed it 
in the transmitting tube manual! Its main advantage was that one tube could do 
the work of several in balanced modulator and mixer service. It was 
Squires-Sanders that thought of using it as a receiver tube if my info is correct.

One problem I have had with premixer designs is that *any* impurity in the 
premixer chain results in mixer degradation. I suspect this is one reason 
premixer designs didn't get used more - only Drake used them extensively.  Collins 
and many others (including Squires Sanders) used dual conversion rather than 
premixing.

Back about 1990 I came across the 1400 kc. filters that are the heart of the 
Type 7. An early attempt to use them ended in dismal failure. In that design, 
which was never assigned a number, the VFO tuned 5.1 to 5.4 MHz, and was 
premixed with either a 7.5 or 13.8 MHz xtal.

7.5 minus 5.1 to 5.4 equals 2.4 to 2.1 (3.8 to 3.5 tuned range)
13.8 minus 5.1 to 5.4 equals 8.7 to 8.4 (7.3 to 7.0)
7.5 plus 5.1 to 5.4 equals 12.6 to 12.9 (14.0 to 14.3

Looked nice on paper but worked terrible. Maybe somebody else could do 
better.

73 de Jim, N2EY


From waltah at earthlink.net  Sun Nov 14 21:20:19 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Sun Nov 14 21:26:02 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 18
In-Reply-To: <419500CE.16699.18B2A46@localhost>
References: <4179920F.4534.FA4D9@localhost>
Message-ID: <4197CC13.10656.291EFE1@localhost>

'Some progress' edition.

With the antenna signal applied to one of the 6JH8 deflection 
plates (and assorted tweeking) the sensitivity is about back to 
where it was and the receiver sounds really great -- better than 
anything else I've got.    Testing time ... I hooked up my two 
homebrew signal generators through the homebrew hybrid 
combiner, dialed up 3800 and 3820 and the strongest signals 
they're able to deliver:  IFDR 77 db.   Not great, but another notch 
better.   

Unfortunately there's not enough gain to use these generators to 
test at higher levels so it would be possible to determine if the 
problem was in the receiver or was due to bad signals from the test 
setup.   

One way the test signals can be bad is if they contain harmonics.   
I built a 7-element lowpass filter (think: two pi nets hooked end to 
end) designed to pass the 75 meter band and kill 40 (where the 
second harmonic of my test sigs would be.   Gee, when I hook an 
antenna through it to the receiver, 80 is unaffected and 40 is gone.  
 These are already *very good* signals; running through that, 
there'll be no significant harmonic content at all.

That got the measured IFDR up to 81 db -- slightly the best figure 
for any receiver here, but I don't have anything really good.   

The way to pin down the bad guy is to do the test again at higher 
power levels.   Three or four tests, say, one at the noise floor, one 
at S-1, and one each at two S-unit intervals to S-9 and in general 
agreement, confirm the limit as being in the receiver.   If these 
measurements do *not* agree, the trouble is somewhere in the test 
setup or (for complex receivers) possibly in a receiver oddity.

A low pass filter gets rid only of harmonic issues in the test 
signals.  (This could be caused by a non-linear amplifier in the test 
set, in fact, a little non-linearity is basically certain to be present, 
even in a class 'A' amp with a tuned output circuit.)   If, however, 
the basic problem is non-linearity of the combiner or 
crossmodulation of the signal generators, then we're looking at the 
two intended signals at 3800, 3820, being accompanied by 
spurious signals at 3780 and 3840 as they come into the set.  
There's no way to get rid of those with a low-pass filter!

Higher receiver gain will allow testing at higher levels of mixer 
overload and since the receiver does need more gain, that's the 
next step.   However, the needed gain is in the range 10-20 db and 
the max increase in IFDR I can measure is only as great as the 
increase of the gain.   To get beyond that, I'll need to modify the 
generators for higher output -- say 1 volt p-p signals instead of 
100,000 uV.   That's tougher than it sounds because the 
generators must also have very high isolation between the non-
linear part of the generator (the tubes) and the output jack.   

Because tubes are non-linear, if you feed a signal in at the output 
jack of a sig gen, it will modulate the signal produced by the 
generator and in IFDR testing, that modulated signal looks exactly 
like the bad signal produced by a non-linear mixer in the receiver.   
So the tubes in two signal generators used for this kind of testing 
must be unable to 'see' each other.   

Part of the job is done by the hybrid combiner -- a weird little circuit 
using a small transformer and a couple of resistors that (ideally) 
takes 1/4 the power from each generator and adds those two sigs 
together at the output jack (a hybrid combiner has two input jacks 
and one output) and throws all the rest of the power away, so 
neither input jack (signal generator) sees anything from the other 
one.

However, practical combiners don't provide much more than 40 db 
isolation between input ports.   So the signal generators 
themselves need to provide isolation.   It's conventionally done with 
a voltage divider.    My homebrew generators produce a 30-volt p-p 
signal and a chain of resistors takes that down to 100,000 uV 
across 50 ohms.   That's most of 50 db additional, giving (with the 
combiner) maybe 90 db isolation beween each generator and the 
output signal of the other. 

You can see the practical problem of increasing generator power.  
If I don't change anything else, then stepping up to 1V p-p output 
requires a 300-volt p-p signal on the voltage divider.   Among other 
nasty problems, what kind of sheilding will it take to keep that 
bottled up inside the sig gen case, so it won't go right past the 
attenuators?   I'm using well-shielded military signal gen cases, but 
they're not *that* well shielded!

Even deciding to use less isolation won't work very well because a 
lower series resistance in the voltage divider chain will lower the Q 
of the amplifier tuned circuit, increasing any waveform distortion.

I'm not eager to start on signal generator power increases.

Another problem is that the receiver crystal filter is right behind the 
first mixer.   With a highly linear mixer, what's to stop a powerful 
input signal from destroying the CF?   Adding an AGC-controlled 
RF stage will help for in-channel signals, however nearby out-of-
channel signals don't produce AGC voltage.   Very high 
performance receivers deal with this by putting a local AGC loop in 
the front end so that *any* extremely strong signal getting through 
the tuned circuits reduces the RF stage gain.   Typically these 
circuits start to take effect around S-9 to S-9+40 and they 
introduce their own set of new issues.  

Fortunately the filter I'm using is stolen from a Tempo-One which is 
a single conversion set.   So it should be a fairly robust filter.

Next step: adding an RF stage.

Walt 
KJ4KV

From yir at scn.org  Mon Nov 15 02:40:52 2004
From: yir at scn.org (YIR)
Date: Mon Nov 15 02:47:16 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 18
References: <4179920F.4534.FA4D9@localhost> <4197CC13.10656.291EFE1@localhost>
Message-ID: <001201c4cae6$a60300c0$6501a8c0@2565128zh5z1wf>

I am following your work on this project using the 6JH8 / 7360 series
mixers with great interest. You are actually doing what I am always
trying to find time for.  So for the time being I am vicariously
enjoying the work of your hands and your willingness to also put it out
here for the rest of us.  I am curious if you have actually measured
90 db with your same test setup on the R-390.
I have the schematic of the Squires Sanders SS-1R but don't yet have
it scanned or I would send it along also in case you don't have it.
By the way its 7360 mixers use 140 volts on the plates and 25 volts
on the deflection plates.  If you need other data from the manual
maybe I can help.

73,  Pat  K7YIR



----- Original Message ----- 
From: <waltah@earthlink.net>
To: <hbr@mailman.qth.net>
Sent: Sunday, November 14, 2004 6:20 PM
Subject: [HBR] Another Receiver Project -- HBR-4, Part 18


> 'Some progress' edition.
>
> With the antenna signal applied to one of the 6JH8 deflection
> plates (and assorted tweeking) the sensitivity is about back to
> where it was and the receiver sounds really great -- better than
> anything else I've got.    Testing time ... I hooked up my two
> homebrew signal generators through the homebrew hybrid
> combiner, dialed up 3800 and 3820 and the strongest signals
> they're able to deliver:  IFDR 77 db.   Not great, but another notch
> better.
>
> Unfortunately there's not enough gain to use these generators to
> test at higher levels so it would be possible to determine if the
> problem was in the receiver or was due to bad signals from the test
> setup.
>
> One way the test signals can be bad is if they contain harmonics.
> I built a 7-element lowpass filter (think: two pi nets hooked end to
> end) designed to pass the 75 meter band and kill 40 (where the
> second harmonic of my test sigs would be.   Gee, when I hook an
> antenna through it to the receiver, 80 is unaffected and 40 is gone.
> These are already *very good* signals; running through that,
> there'll be no significant harmonic content at all.
>
> That got the measured IFDR up to 81 db -- slightly the best figure
> for any receiver here, but I don't have anything really good.
>
> The way to pin down the bad guy is to do the test again at higher
> power levels.   Three or four tests, say, one at the noise floor, one
> at S-1, and one each at two S-unit intervals to S-9 and in general
> agreement, confirm the limit as being in the receiver.   If these
> measurements do *not* agree, the trouble is somewhere in the test
> setup or (for complex receivers) possibly in a receiver oddity.
>
> A low pass filter gets rid only of harmonic issues in the test
> signals.  (This could be caused by a non-linear amplifier in the test
> set, in fact, a little non-linearity is basically certain to be present,
> even in a class 'A' amp with a tuned output circuit.)   If, however,
> the basic problem is non-linearity of the combiner or
> crossmodulation of the signal generators, then we're looking at the
> two intended signals at 3800, 3820, being accompanied by
> spurious signals at 3780 and 3840 as they come into the set.
> There's no way to get rid of those with a low-pass filter!
>
> Higher receiver gain will allow testing at higher levels of mixer
> overload and since the receiver does need more gain, that's the
> next step.   However, the needed gain is in the range 10-20 db and
> the max increase in IFDR I can measure is only as great as the
> increase of the gain.   To get beyond that, I'll need to modify the
> generators for higher output -- say 1 volt p-p signals instead of
> 100,000 uV.   That's tougher than it sounds because the
> generators must also have very high isolation between the non-
> linear part of the generator (the tubes) and the output jack.
>
> Because tubes are non-linear, if you feed a signal in at the output
> jack of a sig gen, it will modulate the signal produced by the
> generator and in IFDR testing, that modulated signal looks exactly
> like the bad signal produced by a non-linear mixer in the receiver.
> So the tubes in two signal generators used for this kind of testing
> must be unable to 'see' each other.
>
> Part of the job is done by the hybrid combiner -- a weird little circuit
> using a small transformer and a couple of resistors that (ideally)
> takes 1/4 the power from each generator and adds those two sigs
> together at the output jack (a hybrid combiner has two input jacks
> and one output) and throws all the rest of the power away, so
> neither input jack (signal generator) sees anything from the other
> one.
>
> However, practical combiners don't provide much more than 40 db
> isolation between input ports.   So the signal generators
> themselves need to provide isolation.   It's conventionally done with
> a voltage divider.    My homebrew generators produce a 30-volt p-p
> signal and a chain of resistors takes that down to 100,000 uV
> across 50 ohms.   That's most of 50 db additional, giving (with the
> combiner) maybe 90 db isolation beween each generator and the
> output signal of the other.
>
> You can see the practical problem of increasing generator power.
> If I don't change anything else, then stepping up to 1V p-p output
> requires a 300-volt p-p signal on the voltage divider.   Among other
> nasty problems, what kind of sheilding will it take to keep that
> bottled up inside the sig gen case, so it won't go right past the
> attenuators?   I'm using well-shielded military signal gen cases, but
> they're not *that* well shielded!
>
> Even deciding to use less isolation won't work very well because a
> lower series resistance in the voltage divider chain will lower the Q
> of the amplifier tuned circuit, increasing any waveform distortion.
>
> I'm not eager to start on signal generator power increases.
>
> Another problem is that the receiver crystal filter is right behind the
> first mixer.   With a highly linear mixer, what's to stop a powerful
> input signal from destroying the CF?   Adding an AGC-controlled
> RF stage will help for in-channel signals, however nearby out-of-
> channel signals don't produce AGC voltage.   Very high
> performance receivers deal with this by putting a local AGC loop in
> the front end so that *any* extremely strong signal getting through
> the tuned circuits reduces the RF stage gain.   Typically these
> circuits start to take effect around S-9 to S-9+40 and they
> introduce their own set of new issues.
>
> Fortunately the filter I'm using is stolen from a Tempo-One which is
> a single conversion set.   So it should be a fairly robust filter.
>
> Next step: adding an RF stage.
>
> Walt
> KJ4KV
>
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via 
> http://mailman.qth.net/mailman/listinfo/hbr
>
> 

From waltah at earthlink.net  Mon Nov 15 17:11:13 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Mon Nov 15 17:17:10 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 18
In-Reply-To: <001201c4cae6$a60300c0$6501a8c0@2565128zh5z1wf>
Message-ID: <4198E331.5001.19E5FBD@localhost>

Pat, K7YIR wrote:
> I am following your work on this project using the 6JH8 / 7360 series
> mixers with great interest. You are actually doing what I am always
> trying to find time for.  So for the time being I am vicariously
> enjoying the work of your hands and your willingness to also put it out
> here for the rest of us. 

The pleasure is of course mine.  The encouragement from the list 
helps keep me going and the suggestions help me stay on the 
right track.

> I am curious if you have actually measured 90 db with your same
> test setup on the R-390. 

No, and I was wrong.  I thought I was using a number from 
Sherwood Engineering's fine site at:

http://sherweng.com/table.html

But when I went there just now and checked, the R-390A IFDR at 
20 kcs spacing is 81 db.   They don't give a number for the R-390.  

I should have known better than to trust my memory.  Glad you 
asked ...

The highest number on the site is the Icom IC-7800 at 102 db, 
followed by the AOR 7030 and something called a KWZ-30, both at 
100.   There are a number of fairly recent sets in the mid to upper 
90's.  The Elecraft K2 (s/n 3170) is very impressive at 98 db ... gee, 
that's a *kit*, folks.

I believe the top vaccum tube numbers are those of the Collins 75 
S3B at 88 db and the Drake R4C at 85.   Neither is a remarkable 
design; it ought to be possible to beat them.   They haven't tested 
the SS-1R.

The G2DAF Mk II receiver certainly holds the top claim, at ~100 
db.   The design seems consistent with excellent performance.   
Unfortunately very few of them seem to have been built.

> I have the schematic of the Squires Sanders SS-1R but don't yet have
> it scanned or I would send it along also in case you don't have it.

I do have it, probably from the BAMA site -- but thank you.   They 
also put the antenna signal on G1 of the 7360.   Gee, I'd like to talk 
to one of those designers about the reason for that.  Either there's 
something I'm missing, or one guy made a mistake and everyone 
else followed.   I can't find a single major advantage to G1 antenna 
signal input, and the linearity seems markedly better doing it the 
other way.

(The minor advantage is you do get good rejection of feed-through 
on the IF if you balance the output from the mixer.   But most 
designs didn't do that and I don't see this as compelling, compared 
to dynamic range.   *Every* receiver has IF feed-through to contend 
with, for goshsakes.

I'm having a hard time getting started on the RF stage of the HBR-
4.   There's plenty of room for it (and I've punched the socket hole) 
but the trimmer and bandswitch layout there isn't going to be good 
for stability.   I'm sure that before I'm finished I'll have to completely 
redo that, to get more spacing and put in some shielding.  So I'm 
struggling with just biting the bullet and starting with a 6EH7 stage 
which (even at low gain) will likely force the whole job to be done 
before I have any results, or using a cathode-coupled 6ES8 as a 
starting point.   Because there's no phase reversal, this should be 
stable at reasonably low gain even in the existing configuration.  

An interconnected issue is exactly how to install the necessary 9 
mcs trap(s).   A parallel tuned trap can be put in the antenna lead 
to the antenna coil.   A twin-triode RF stage (either cathode 
coupled or cascode) allows a second similar trap between the 
sections; if using a 6EH7, there's no easy equivalent.   

With a single conversion design at least the trap need only be for a 
fixed frequency, meaning I can go for max Q and need not provide 
much of a tuning range.   I guess the thing to do is to install the 
antenna lead trap to start with and hope that that's all that is 
needed.  

Both ends of the trap are hot -- hafta build that on spacers or a 
terminal strip or something.   At least there are no strong signals at 
9 Mcs in this location -- nothing like 'World Harvest Radio' at 5820 
or whatever it was, with the HBR-2K's 5520-6020 kcs tunable first 
IF.   

Walt 
KJ4KV



From windy10605 at juno.com  Mon Nov 15 21:39:14 2004
From: windy10605 at juno.com (windy10605@juno.com)
Date: Mon Nov 15 21:45:36 2004
Subject: [HBR] another two HBRs
Message-ID: <20041115.203915.488.1.windy10605@juno.com>

Looks like e-Bay has another two HBR receivers for sale and one might be
Alexander Stewart's (WA4ZNI) HBR-13C from the articles in QST. 
One of you guys should pick that one up, it's a little beyond my means $$
for 6 days left in the auction.

73 Kees K5BCQ  
From hbrnut at earthlink.net  Tue Nov 16 20:01:12 2004
From: hbrnut at earthlink.net (Darrell, WA5VGO)
Date: Tue Nov 16 20:06:16 2004
Subject: [HBR] another two HBRs
In-Reply-To: <20041115.203915.488.1.windy10605@juno.com>
Message-ID: <5.2.0.9.2.20041116185817.00baf7b0@mail.earthlink.net>

There are three HBR's on eBay now. Two HBR-13C's and one HBR-11. The HBR-11 
auction ends in a few hours.

73,
Darrell, WA5VGO





At 08:39 PM 11/15/2004 -0600, windy10605@juno.com wrote:
>Looks like e-Bay has another two HBR receivers for sale and one might be
>Alexander Stewart's (WA4ZNI) HBR-13C from the articles in QST.
>One of you guys should pick that one up, it's a little beyond my means $$
>for 6 days left in the auction.
>
>73 Kees K5BCQ
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>construction notes...... via http://www.qsl.net/k5bcq/
>
>Retrieve reflector archived data via 
>http://mailman.qth.net/mailman/listinfo/hbr



From waltah at earthlink.net  Wed Nov 17 13:08:09 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Wed Nov 17 13:14:43 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 19
In-Reply-To: <4197CC13.10656.291EFE1@localhost>
References: <419500CE.16699.18B2A46@localhost>
Message-ID: <419B4D39.5236.E92A22@localhost>

'More progress and another realization.'

I had planned a parallel trap in series with the antenna lead placed 
between the BNC connector and the link on the coil.  Unfortunately 
in that position the reactance changes so wildly, both due to 
reflection from the antenna coil and the antenna itself, that there 
was no one correct setting of the trap -- it depended on the band 
and the exact tuning of the antena coil.   Using a series trap 
across the antenna connection (with much higher reactances) 
make things much better -- good enough to be satisfactory.

I put in a cathode-coupled 6ES8 RF stage.   The antenna coil feeds 
a cathode follower which drives the second half as a conventional 
triode RF amp.   After fixing a problem caused by inadequate 
bypassing of the AGC line to the second triode (the c.f. is not on 
AGC) it is perfectly stable on 80 through 20M;  later today I'll tune 
up the other bands and see if there are problems there.

The gain seems ample; if I now reduce the IF gain, the mixer noise 
should disappear.  Have to add a pot to adjust the gain of the 
second IF stage from the back panel so that S-9 = 100 uV. 

It was nice this morning to be able to hear a VK on 75 and realize 
that our bands were back in operation after a week of absence due 
to a solar flare.

In addition to adjusting overall gain and checking stability, I need to 
check the sensitivity (which should be improved) and the dynamic 
range (hopefully unhurt and with luck I might now have enough 
signal generator power to measure a higher number than before.)

Then it will be time to plow ahead with returning the premixer to the 
two-6J6 configuration.   With the higher sensitivity, the spurious 
response caused by direct conversion by the VFO (without the 
intervention of the crystal oscillator) is now easily heard.   The 
former configuration -- a doubly balanced premixer with four triodes -
- killed that, and I need to go back there again.   Another couple of 
days work, I expect -- have to make a plate to mount the two 
sockets, completely rewire, replace the trimmer board, wind a new 
coil ... like, *total* makeover.

At the same time I want to increase the output of the premixer.   
The mixer should be operating in switching mode and something 
like 10V p-p is required to do that.

This premixer layout will be a little different because driving G1 of 
the mixer requires only single-ended output.   So that puts all four 
premixer triode plates in parallel -- relatively a lot of capacity for a 
circuit that goes up to 39 Mcs.  The good news is that the 6J6 
plate capacitance (to all other electrodes) is only 0.4 mmf/section if 
you don't use a shield and only around 1.2 if you shield it.   That 
won't be a problem.

Another possibility is a single twin triode with independent 
cathodes (say a 12AT7), driving the grids from the VFO and the 
cathodes from a center tapped winding on the crystal oscillator 
plate coil.  However it's harder to drive cathodes than grids and 
there may be a problem getting enough power.   Probably I should 
start with a 6922 premixer -- that's like a 6DJ8 but with a lower 
current filament.

The premixer doesn't really have to be balanced against the crystal 
oscillator.   That frequency is 14 Mcs above the channel so not 
likely to cause problems.  But because 'a mixer is a multiplier,' 
adding signals in the plate circuit for single ended output requires 
that both input signals be supplied in push-pull.   

And the realization:  with the shift from G1 to the deflection plates 
for the antenna input to the 6JH8 mixer, I have the choice of push-
pull signal drive.   Meaning that a push-pull RF stage could be 
used, as in the G2DAF design.  *That* ought to be a real killer 
design, since push-pull stages tend to cancel out even harmonic 
distortion and the second harmonic plays a major role in third-order 
intermodulation distortion.  

It can't be done in this set without major changes.   A push-pull RF 
stage needs balanced tank circuits and having used the FT-101 
slug tuning front end parts makes that impossible.   But a similar 
overall configuration using a four-gang tuning cap and fixed coils for 
the front end (as in the G2DAF) would do it and would fit just fine in 
the same basic layout.  

There's miles to go before that becomes an issue.  I don't even 
know for sure that the present single-ended RF amp will be the 
limitation of this design, though with a mixer capable of handling 
~40-volt swing, the limit certainly should be the RF amp.   

Walt
KJ4KV


From jm_lekostaj at attglobal.net  Wed Nov 17 16:44:37 2004
From: jm_lekostaj at attglobal.net (Joe LeKostaj)
Date: Wed Nov 17 16:49:33 2004
Subject: [HBR] questions about HBR-11
Message-ID: <p05010404bdc167e16e33@[192.168.1.4]>

Howdy. I've got a few questions about the HBR-11 that I hope you 
who've already been down this path can answer.

1) Can I use the relatively large IF transformers (85 kc) from a 
BC453-type receiver in the HBR-11 rather than the smaller 3/4 inch 
transformers originally specified? In other words, was size the main 
reason for using small 3/4 inch transformers in the original 
HBR-8/11/13 article?

2) The HBR-11 uses three transformers in the 100 kc IF. Can the one 
BC453 I've got provide all three transformers or do I need a second 
BC453 to have enough of the right type?

3) Has anyone made a 30 meter coil set? Are there any birdies or 
nasty image responses when using an HBR-11 on this band?

4) Pictures of the underside of the HBR-11 show that L4A and L4B (the 
1610 kc IF transformers) do not have shield cans. Is that really how 
they're supposed to be?

5) Has anyone experienced direct IF pickup of the AM broadcast 
stations that are now found between 1600-1700 kc? (I suppose one's 
proximity to such a station would be the main culprit.)

6) It seems the original article did not call for a chassis bottom 
cover, is that correct?

Hoping to build an HBR-11 one of these years.....  ;-)

73,
Joe K9LY
From hbrnut at earthlink.net  Wed Nov 17 20:55:59 2004
From: hbrnut at earthlink.net (Darrell, WA5VGO)
Date: Wed Nov 17 21:01:14 2004
Subject: [HBR] questions about HBR-11
In-Reply-To: <p05010404bdc167e16e33@[192.168.1.4]>
Message-ID: <5.2.0.9.2.20041117194202.00bc2a90@mail.earthlink.net>

Joe,

No one is jumping on this, so let me throw out a few opinions.

1) The IF transformers from a BC453 work very well. Many people have used 
them successfully, so you won't be in uncharted waters if you go this route.

2)  I see no reason you can't use all three from the same BC453, although 
using all input transformers might give you a little better ultimate 
selectivity.

3) Haven't tried it.

4) They are unshielded, just like the photos depict.

5) I haven't had this problem although (just as you stated) if you are in 
close proximity to one it could be a problem.

6) The article does not call for one, but I found that adding one stiffened 
up the chassis and made a very significant improvement in mechanical stability.

The only thing I will add is, as I have stated on this reflector before, 
the hang AGC makes such a major improvement in the overall performance, I 
wouldn't think of building one without it.

Maybe some others will get in here and give their opinions.

73,
Darrell, WA5VGO




At 03:44 PM 11/17/2004 -0600, you wrote:
>Howdy. I've got a few questions about the HBR-11 that I hope you who've 
>already been down this path can answer.
>
>1) Can I use the relatively large IF transformers (85 kc) from a 
>BC453-type receiver in the HBR-11 rather than the smaller 3/4 inch 
>transformers originally specified? In other words, was size the main 
>reason for using small 3/4 inch transformers in the original HBR-8/11/13 
>article?
>
>2) The HBR-11 uses three transformers in the 100 kc IF. Can the one BC453 
>I've got provide all three transformers or do I need a second BC453 to 
>have enough of the right type?
>
>3) Has anyone made a 30 meter coil set? Are there any birdies or nasty 
>image responses when using an HBR-11 on this band?
>
>4) Pictures of the underside of the HBR-11 show that L4A and L4B (the 1610 
>kc IF transformers) do not have shield cans. Is that really how they're 
>supposed to be?
>
>5) Has anyone experienced direct IF pickup of the AM broadcast stations 
>that are now found between 1600-1700 kc? (I suppose one's proximity to 
>such a station would be the main culprit.)
>
>6) It seems the original article did not call for a chassis bottom cover, 
>is that correct?
>
>Hoping to build an HBR-11 one of these years.....  ;-)
>
>73,
>Joe K9LY
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>construction notes...... via http://www.qsl.net/k5bcq/
>Retrieve reflector archived data via 
>http://mailman.qth.net/mailman/listinfo/hbr
>



From windy10605 at juno.com  Wed Nov 17 21:01:55 2004
From: windy10605 at juno.com (windy10605@juno.com)
Date: Wed Nov 17 21:08:52 2004
Subject: Fw: Re: [HBR] questions about HBR-11
Message-ID: <20041117.200156.2352.9.windy10605@juno.com>

We were all waiting for the BC-453 IF can expert to jump in, Darrell.
Nice ID.

73 Kees K5BCQ


--------- Forwarded message ----------
From: "Darrell, WA5VGO" <hbrnut@earthlink.net>
To: HBR Receiver List <hbr@mailman.qth.net>
Date: Wed, 17 Nov 2004 19:55:59 -0600
Subject: Re: [HBR] questions about HBR-11
Message-ID: <5.2.0.9.2.20041117194202.00bc2a90@mail.earthlink.net>

Joe,

No one is jumping on this, so let me throw out a few opinions.

1) The IF transformers from a BC453 work very well. Many people have used

them successfully, so you won't be in uncharted waters if you go this
route.

2)  I see no reason you can't use all three from the same BC453, although

using all input transformers might give you a little better ultimate 
selectivity.

3) Haven't tried it.

4) They are unshielded, just like the photos depict.

5) I haven't had this problem although (just as you stated) if you are in

close proximity to one it could be a problem.

6) The article does not call for one, but I found that adding one
stiffened 
up the chassis and made a very significant improvement in mechanical
stability.

The only thing I will add is, as I have stated on this reflector before, 
the hang AGC makes such a major improvement in the overall performance, I

wouldn't think of building one without it.

Maybe some others will get in here and give their opinions.

73,
Darrell, WA5VGO




At 03:44 PM 11/17/2004 -0600, you wrote:
>Howdy. I've got a few questions about the HBR-11 that I hope you who've 
>already been down this path can answer.
>
>1) Can I use the relatively large IF transformers (85 kc) from a 
>BC453-type receiver in the HBR-11 rather than the smaller 3/4 inch 
>transformers originally specified? In other words, was size the main 
>reason for using small 3/4 inch transformers in the original HBR-8/11/13

>article?
>
>2) The HBR-11 uses three transformers in the 100 kc IF. Can the one
BC453 
>I've got provide all three transformers or do I need a second BC453 to 
>have enough of the right type?
>
>3) Has anyone made a 30 meter coil set? Are there any birdies or nasty 
>image responses when using an HBR-11 on this band?
>
>4) Pictures of the underside of the HBR-11 show that L4A and L4B (the
1610 
>kc IF transformers) do not have shield cans. Is that really how they're 
>supposed to be?
>
>5) Has anyone experienced direct IF pickup of the AM broadcast stations 
>that are now found between 1600-1700 kc? (I suppose one's proximity to 
>such a station would be the main culprit.)
>
>6) It seems the original article did not call for a chassis bottom
cover, 
>is that correct?
>
>Hoping to build an HBR-11 one of these years.....  ;-)
>
>73,
>Joe K9LY
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>construction notes...... via http://www.qsl.net/k5bcq/
>Retrieve reflector archived data via 
>http://mailman.qth.net/mailman/listinfo/hbr
>



************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
construction notes...... via http://www.qsl.net/k5bcq/ 

Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
From waltah at earthlink.net  Wed Nov 17 22:39:55 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Wed Nov 17 22:46:13 2004
Subject: [HBR] questions about HBR-11
In-Reply-To: <p05010404bdc167e16e33@[192.168.1.4]>
Message-ID: <419BD33B.20248.2F4B650@localhost>

Joe LeKostaj wrote:
> 4) Pictures of the underside of the HBR-11 show that L4A and L4B (the 
> 1610 kc IF transformers) do not have shield cans. Is that really how 
> they're supposed to be?
> 
> 5) Has anyone experienced direct IF pickup of the AM broadcast 
> stations that are now found between 1600-1700 kc? (I suppose one's 
> proximity to such a station would be the main culprit.)

The first bit of research I'd do is take a modern digitally tuned radio 
(so you can get precise frequencies) and inventory stations in the 
area you're in.   Then when you build, jigger the 1610 IF (if 
necessary) to be in the biggest hole you can find nearby.   

Note that you don't want to get on a multiple of the 2nd IF, either 
because that may give you pickup of the BFO.  For the 100 kcs IF 
that means avoid 1600 and 1700; for 85 kcs it would be 1615 and 
1700 if my mental math is right.   I used 1660 Kcs in my (sort of) 
HBR 13 project.
 
Commercial IFTs have a pretty wide tuning range so this won't be a 
big problem.  The 85 Kcs units are tougher -- they have just a 
couple kcs of tuning range and if you use a crystal for the 2nd 
oscillator you'll wind up having to make the final adjustment of the 
1st IF so it will match the crystal/85 Kcs IFT combination.  

You're really better off with using just the 85 Kcs units from a 
single receiver.   Mine were junkbox units from who knows what 
receivers and I wound up having to go in and tweak the fixed caps 
in there to get them all to where they'd tune the same freq.  

Returning to the local BC station issue, it's not just direct pick up 
you have to be concerned about.   A good ham antenna is not that 
bad a BC antenna and it's perfectly possible for a local station to 
blast right through the front end of your receiver and enter the 1st IF 
by that route.   You can use a trap or low pass filter to control this, 
but it's best to start by putting the IF as far from such signals as 
you can.

Walt
KJ4KV
From jm_lekostaj at attglobal.net  Thu Nov 18 14:14:52 2004
From: jm_lekostaj at attglobal.net (Joe LeKostaj)
Date: Thu Nov 18 14:19:59 2004
Subject: [HBR] questions about HBR-11
In-Reply-To: <5.2.0.9.2.20041117194202.00bc2a90@mail.earthlink.net>
References: <5.2.0.9.2.20041117194202.00bc2a90@mail.earthlink.net>
Message-ID: <p05010408bdc27c23045c@[192.168.1.4]>

Thanks for the replies!

Follow-up questions for Darrell:

If I use the 85 kc transformers in the HBR in the same order (input 
to output) as in the BC-453, that should be a pretty safe bet, yes?

Also, could you please point me to the hang AGC info?

Regarding local AM stations, there's one on 1590 that may casue some 
trouble. We'll just have to see how it goes.

Tnx & 73,
Joe K9LY



At 7:55 PM -0600 11/17/04, Darrell, WA5VGO wrote:
>Joe,
>
>No one is jumping on this, so let me throw out a few opinions.
>
>1) The IF transformers from a BC453 work very well. Many people have 
>used them successfully, so you won't be in uncharted waters if you 
>go this route.
>
>2)  I see no reason you can't use all three from the same BC453, 
>although using all input transformers might give you a little better 
>ultimate selectivity.
>
>3) Haven't tried it.
>
>4) They are unshielded, just like the photos depict.
>
>5) I haven't had this problem although (just as you stated) if you 
>are in close proximity to one it could be a problem.
>
>6) The article does not call for one, but I found that adding one 
>stiffened up the chassis and made a very significant improvement in 
>mechanical stability.
>
>The only thing I will add is, as I have stated on this reflector 
>before, the hang AGC makes such a major improvement in the overall 
>performance, I wouldn't think of building one without it.
>
>Maybe some others will get in here and give their opinions.
>
>73,
>Darrell, WA5VGO
>
>
>
>
>At 03:44 PM 11/17/2004 -0600, you wrote:
>>Howdy. I've got a few questions about the HBR-11 that I hope you 
>>who've already been down this path can answer.
>>
>>1) Can I use the relatively large IF transformers (85 kc) from a 
>>BC453-type receiver in the HBR-11 rather than the smaller 3/4 inch 
>>transformers originally specified? In other words, was size the 
>>main reason for using small 3/4 inch transformers in the original 
>>HBR-8/11/13 article?
>>
>>2) The HBR-11 uses three transformers in the 100 kc IF. Can the one 
>>BC453 I've got provide all three transformers or do I need a second 
>>BC453 to have enough of the right type?
>>
>>3) Has anyone made a 30 meter coil set? Are there any birdies or 
>>nasty image responses when using an HBR-11 on this band?
>>
>>4) Pictures of the underside of the HBR-11 show that L4A and L4B 
>>(the 1610 kc IF transformers) do not have shield cans. Is that 
>>really how they're supposed to be?
>>
>>5) Has anyone experienced direct IF pickup of the AM broadcast 
>>stations that are now found between 1600-1700 kc? (I suppose one's 
>>proximity to such a station would be the main culprit.)
>>
>>6) It seems the original article did not call for a chassis bottom 
>>cover, is that correct?
>>
>>Hoping to build an HBR-11 one of these years.....  ;-)
>>
>>73,
>>Joe K9LY
>>************************************
>>Visit the HBR Receiver Web Site with over 100 pictures of receivers 
>>and construction notes...... via http://www.qsl.net/k5bcq/
>>Retrieve reflector archived data via 
>>http://mailman.qth.net/mailman/listinfo/hbr
>>
>
>
>
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers 
>and construction notes...... via http://www.qsl.net/k5bcq/
>Retrieve reflector archived data via 
>http://mailman.qth.net/mailman/listinfo/hbr

From waltah at earthlink.net  Thu Nov 18 16:28:22 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Thu Nov 18 16:34:54 2004
Subject: [HBR] questions about HBR-11
In-Reply-To: <p05010408bdc27c23045c@[192.168.1.4]>
References: <5.2.0.9.2.20041117194202.00bc2a90@mail.earthlink.net>
Message-ID: <419CCDA6.29755.D26C2E@localhost>

Joe LeKostaj wrote:
> Also, could you please point me to the hang AGC info?

If you have a *Handbook* from the 60's, it should be in there.   My 
1967 book has it on p. 106.  The vacuum diodes can be replaced 
by silicon units;  only the one shown as part of a 6BC7 needs any 
particular voltage rating and since this is audio-based AGC, you 
could use any of the popular 400-volt rectifier diodes there. 

Since you need one of the triodes to drive any audio AGC scheme, 
you're really just talking three more diodes, another triode, and a 
few other small parts to put in hang AGC.   It's a very nice addition.

Of course if you use a standard audio AGC circuit -- the HB-67 in 
the same book shows one -- you can wait until you have the set 
working and retrofit 'hang' AGC.   Just leave a little 'real estate' near 
the AGC driver tube and provide or leave room for an extra triode 
there.   

Boy, the HB-67 uses a rare tube.  The 6T9 is one of those 10-pin 9-
pin tubes, isn't it?  Has anyone *ever* seen the socket one of those 
things?
   
> 
> Regarding local AM stations, there's one on 1590 that may casue some 
> trouble. We'll just have to see how it goes.

You're in pretty good shape.    With the 85 Kcs IFTs I'd put the 1st 
IF about halfway between multiples -- 19 x 85 = 1615 and 20 x 85 
= 1700, so something about 1660.   That leaves you a couple of 
kcs to tune the 85 kcs BFO before the harmonic is centered in the 
1st IF and it is well away from 1590.   

Of course a well-filtered and shielded BFO running at just high 
enough power to do the job shouldn't leak harmonics back to the 
1st IF, but there's no point in making the job harder instead of 
easier!

Walt
KJ4KV
From hbrnut at earthlink.net  Thu Nov 18 19:15:57 2004
From: hbrnut at earthlink.net (Darrell, WA5VGO)
Date: Thu Nov 18 19:21:22 2004
Subject: [HBR] questions about HBR-11
In-Reply-To: <p05010408bdc27c23045c@[192.168.1.4]>
References: <5.2.0.9.2.20041117194202.00bc2a90@mail.earthlink.net>
	<5.2.0.9.2.20041117194202.00bc2a90@mail.earthlink.net>
Message-ID: <5.2.0.9.2.20041118180627.00bb2568@mail.earthlink.net>

Joe,

I would use them in the same order as the BC-453. The coupling should 
presumably be optimum like that.

The hang AGC circuit can be found on Kee's HBR web site. Check out the 
schematic for the W7QBR improved HBR-16. The only thing I found was that it 
performed much better connected to the IF instead of using the audio. The 
attack was much faster and I got rid of some BFO leakage that was occurring.

One more passing thought. If you plan on using it on the higher bands(say, 
above 20 meters), Going to the Hartley oscillator and the additional gain 
it provides is very worthwhile. On the other hand, if you are only going to 
use it on 20 meters and below, the receiver has more than adequate gain 
without it.

73,
Darrell, WA5VGO






At 01:14 PM 11/18/2004 -0600, you wrote:
>Thanks for the replies!
>
>Follow-up questions for Darrell:
>
>If I use the 85 kc transformers in the HBR in the same order (input to 
>output) as in the BC-453, that should be a pretty safe bet, yes?
>
>Also, could you please point me to the hang AGC info?
>
>Regarding local AM stations, there's one on 1590 that may casue some 
>trouble. We'll just have to see how it goes.
>
>Tnx & 73,
>Joe K9LY
>
>
>
>At 7:55 PM -0600 11/17/04, Darrell, WA5VGO wrote:
>>Joe,
>>
>>No one is jumping on this, so let me throw out a few opinions.
>>
>>1) The IF transformers from a BC453 work very well. Many people have used 
>>them successfully, so you won't be in uncharted waters if you go this route.
>>
>>2)  I see no reason you can't use all three from the same BC453, although 
>>using all input transformers might give you a little better ultimate 
>>selectivity.
>>
>>3) Haven't tried it.
>>
>>4) They are unshielded, just like the photos depict.
>>
>>5) I haven't had this problem although (just as you stated) if you are in 
>>close proximity to one it could be a problem.
>>
>>6) The article does not call for one, but I found that adding one 
>>stiffened up the chassis and made a very significant improvement in 
>>mechanical stability.
>>
>>The only thing I will add is, as I have stated on this reflector before, 
>>the hang AGC makes such a major improvement in the overall performance, I 
>>wouldn't think of building one without it.
>>
>>Maybe some others will get in here and give their opinions.
>>
>>73,
>>Darrell, WA5VGO
>>
>>
>>
>>
>>At 03:44 PM 11/17/2004 -0600, you wrote:
>>>Howdy. I've got a few questions about the HBR-11 that I hope you who've 
>>>already been down this path can answer.
>>>
>>>1) Can I use the relatively large IF transformers (85 kc) from a 
>>>BC453-type receiver in the HBR-11 rather than the smaller 3/4 inch 
>>>transformers originally specified? In other words, was size the main 
>>>reason for using small 3/4 inch transformers in the original HBR-8/11/13 
>>>article?
>>>
>>>2) The HBR-11 uses three transformers in the 100 kc IF. Can the one 
>>>BC453 I've got provide all three transformers or do I need a second 
>>>BC453 to have enough of the right type?
>>>
>>>3) Has anyone made a 30 meter coil set? Are there any birdies or nasty 
>>>image responses when using an HBR-11 on this band?
>>>
>>>4) Pictures of the underside of the HBR-11 show that L4A and L4B (the 
>>>1610 kc IF transformers) do not have shield cans. Is that really how 
>>>they're supposed to be?
>>>
>>>5) Has anyone experienced direct IF pickup of the AM broadcast stations 
>>>that are now found between 1600-1700 kc? (I suppose one's proximity to 
>>>such a station would be the main culprit.)
>>>
>>>6) It seems the original article did not call for a chassis bottom 
>>>cover, is that correct?
>>>
>>>Hoping to build an HBR-11 one of these years.....  ;-)
>>>
>>>73,
>>>Joe K9LY
>>>************************************
>>>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>>>construction notes...... via http://www.qsl.net/k5bcq/
>>>Retrieve reflector archived data via 
>>>http://mailman.qth.net/mailman/listinfo/hbr
>>
>>
>>
>>************************************
>>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>>construction notes...... via http://www.qsl.net/k5bcq/
>>Retrieve reflector archived data via 
>>http://mailman.qth.net/mailman/listinfo/hbr
>
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>construction notes...... via http://www.qsl.net/k5bcq/
>Retrieve reflector archived data via 
>http://mailman.qth.net/mailman/listinfo/hbr
>



From N2EY at aol.com  Thu Nov 18 21:54:57 2004
From: N2EY at aol.com (N2EY@aol.com)
Date: Thu Nov 18 22:00:29 2004
Subject: [HBR] questions about HBR-11
Message-ID: <30.65e5ea79.2eceba81@aol.com>

In a message dated 11/18/04 4:35:45 PM Eastern Standard Time, 
waltah@earthlink.net writes:


> Boy, the HB-67 uses a rare tube.  The 6T9 is one of those 10-pin 9-
> pin tubes, isn't it?  Has anyone *ever* seen the socket one of those 
> things?
>    
> 

Oh yes. It's a 12 pin Compactron. 

While not an exact replacement, I think a 6AQ5 is a pretty close match for 
the power pentode side. The triode might be replaced by a 6AT6, with some 
redesign. 

IIRC the 6T9 is used in the audio section so it's not that much of a job to 
redesign it slightly to use available tubes.

73 de Jim, N2EY
From waltah at earthlink.net  Fri Nov 19 14:13:03 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Fri Nov 19 14:19:45 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 20
In-Reply-To: <419B4D39.5236.E92A22@localhost>
References: <4197CC13.10656.291EFE1@localhost>
Message-ID: <419DFF6F.795.1239422@localhost>

'A realization, continued.'

A push-pull RF stage is a good idea but at first it seemed to require 
a major front end redesign, mechanical as well as electrical.   But 
on reflection, maybe not.

Push-pull is a good idea because the natural curvature of tube 
characteristics causes generation of second harmonics at large 
signal levels.   

If you look at the characteristic curves in a tube handbook, the 
spacing of the grid voltage curves isn't uniform.   When you draw a 
straight 'load line' relating plate voltage to grid voltage for a 
particular load, the output voltage steps along that line marked by 
equal changes in grid voltage will not be equal.   In other words, 
distortion will occur and the worst of it will be the second harmonic -
- the big contributor to the third-order intermodulation distortion 
which sets the practical limit on the dynamic range of a 
communications receiver.  

Some tubes are better than others, but such distortion is a fact of 
life in amplifiers and when a wide range of signals must be handled, 
there's no way around it.   

In a push-pull amplifier, however, the two halves swing in opposite 
directions.  Adding the two signals with reversed polarity causes 
the second (and all even-order harmonics) to cancel out.   And in a 
receiver front-end, the result should be much reduced third-order 
IMD.   

The G2DAF Mk II receiver is the only ham set I'm aware of to use a 
push-pull RF stage and it was claimed to hit 100 db dynamic range 
-- the only ham design I'm aware of to make that claim.

Remember the self-inverting amplifiers used in some of the early 
oscilloscopes and some medium-fi and intercom applications?   
The output tubes are connected in push-pull with an unbypassed 
cathode resistor; one grid is grounded and the other one is driven 
by a single-end signal.   Why couldn't the same be done with a 
receiver RF stage?   The signals in the two tubes aren't perfectly 
equal and opposite, but they should be close enough for 
considerable cancellation of distortion.   And no push-pull input 
circuit required.

That leaves the output.   That transformer has to be push-pull, 
because that's where the two distortion signals get cancelled.   But 
why would the push-pull part have to be the tuned part?   What 
about letting the tuned circuit be single ended and just adding a 
center tapped auxilliary winding on the same coil, connected to the 
two plates?   Push-pull output can be taken from the two plates, 
single ended is available from the tuned winding.  

The gain of such an amplifier is that of the single tube with an 
unbypassed cathode resistor of the same impedance but it is 
divided between the two plates.   Should be roughly the same as 
what I have now, since half of the tube is used as a cathode 
follower and thus provides no gain at all.

I had a spare slug-tuned coil and it was the work of a couple of 
hours to tear it apart and add a bifilar center-tapped winding for the 
tube plates.   The next step is rewiring the RF stage to use that 
transformer;  should get that done today.

Depending on the 'luck of the draw' I may have serious instability in 
this stage but reversing the plate connections should deal with it, 
since the poor shielding is between the two tuned circuits.   Even 
in the present non-phase inverting form it is somewhat unstable on 
40 meters where the Q of the coils is at the highest.   I'll load the 
tuned circuit for that band with a resistor as the gain is way higher 
than other bands, anyhow.

In another minor inspiration, I changed the cathode resistor of the 
6JH8 mixer stage from the 330 ohms I had guessed at, to 1200 
ohms as indicated in the recommended balanced mixer circuit for 
the 7360.   That improved the sound of the receiver and in the past, 
better sound has always meant better numbers, once I figured out 
how to measure 'em.   Evidently the 6JH8 and 7360 are more alike 
than different.

Obviously I need to plan to go step-by-step to optimize that 
resistor.   

Signal to noise (sensitivity) is now perfectly satisfactory, I think.  
On any band, disconnecting the antenna greatly reduces the noise 
level.   

This is the best-sounding receiver I've used -- a real pleasure when 
listening in and around the DX window on 80 where most folks take 
clean, clear signals very seriously.   Lots of 'professionalism' (for 
want of a better word) there -- except for that piece of garbage that 
drifted from pile-up to pile-up, tuning up.  Heard last night, 4N600A 
and a few G's.   And that's on my 160M full wave loop at 15' height, 
fed with a twisted pair and tilted (by the slope of the land) toward 
the west.   Gee ... maybe I'll put up an 80M dipole at a little greater 
height.

Looking at the G2DAF transmitter discussion in the RSGB 
Handbook 5th edition, I found a reference to a Mk III version of his 
receiver.   Has anyone ever seen any more than this?   *That* 
would be an interesting design -- unless it's solid state.

Walt
KJ4KV
From windy10605 at juno.com  Fri Nov 19 14:36:55 2004
From: windy10605 at juno.com (windy10605@juno.com)
Date: Fri Nov 19 14:45:21 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 20
Message-ID: <20041119.133656.1688.0.windy10605@juno.com>

After reading all the informative posts and comments from others in the
group, I certainly would like to see a complete schematic when you get
done, Walt. Maybe an article in Electric Radio would be appropriate since
I have not seen any more follow-on articles on the HBR-2000.

73 Kees K5BCQ
From waltah at earthlink.net  Fri Nov 19 16:27:41 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Fri Nov 19 16:34:27 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 20
In-Reply-To: <20041119.133656.1688.0.windy10605@juno.com>
Message-ID: <419E1EFD.1635.19EDCEA@localhost>

Kees:
> After reading all the informative posts and comments from others in the
> group, I certainly would like to see a complete schematic when you get
> done, Walt. 

Fair enough -- and it's a promise.  

> Maybe an article in Electric Radio would be appropriate ...

I agree, and that article has been in progress since the series of 
posts began.   It's a very different piece of writing since it needs to 
present a complete picture of the finished project with only the 
most interesting of the digressions detailed in 20 parts (and 
counting) on the list.   Rather a moving target, even though I don't 
try to keep it up-to-the-moment.  I'm about to go back to it and add 
the discovery that we've all been hooking up our beam tube mixers 
backwards.

I found two more beam tube receiver mixers in the RSGB handbook 
this afternoon -- they're backwards too.   Of course you can argue 
that 'backwards' is relative -- that even if hooked up with G1 as the 
signal input you get a high gain pentode mixer of pretty decent 
performance.   But I'm unable to find *any* general advantage to 
hooking up that way.   

> ... since I have not seen any more follow-on articles on the
> HBR-2000. 

HBR-2K remains an unfinished project.   I need to redo the RF 
stage for higher gain but unfortunately it already has RF 
regeneration so I've got to improve the shielding.   You should only 
see what that entails; it may be possible or it may not.  

In doing that design I completely forgot that the output of the first 
mixer contains a great deal of signal-frequency junk and must 
therefore be carefully isolated from the antenna circuits and RF 
stage.   

I learned a lot about front end layout from that effort and the HBR-4 
project has benefited: It has about twice the real estate for that 
section as compared to the 2K.

I don't think that one will ever get the level of documentation that 
the HBR-4 project should.   It's interesting mainly as an effort to 
translate the FT-101 receiver to vacuum tubes with the minimum of 
changes, for example it uses the same double-conversion scheme. 
I think it could be an excellent performer by the standards of the 
day but it's not there yet.   

And frankly, if I were looking for a project of this complexity I'd far 
rather tackle the HBR-4.   It's capable of a lot more (say an IFDR 
around 100 db instead of maybe 80) and I don't think it would take 
a nickle's worth of extra work, once the glitches are out of the 
design.   

As always, thanks for the encouragement.

Walt 
KJ4KV
From waltah at earthlink.net  Sun Nov 21 12:44:49 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Sun Nov 21 12:52:04 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 21
In-Reply-To: <419DFF6F.795.1239422@localhost>
References: <419B4D39.5236.E92A22@localhost>
Message-ID: <41A08DC1.29619.EF9650@localhost>

'Shhhh ... it doesn't know it isn't push-pull.'

Okay, so actually, the new RF stage *is* push-pull -- sort of.

I used a 6ES8 with the self-inverting input circuit (drive one grid, 
ground the other, leave cathode unbypassed) and fed the two 
plates into a center tapped (bifillar) winding on the existing slug 
tuned output coil.   It would have been tidier to take the output from 
the plate connections straight to the two 6JH8 deflection plates, 
but because of the external coil added in series with the tuned coil 
on 40M and below, the gain on the low bands was too low.   The 
tube works push-pull, but the output is taken single-ended to just 
one of the mixer deflection plates.

That should have all the advantages of a push-pull RF stage 
(cancellation of 2nd harmonics) and I can't think of any real 
disadvantage.   The idea seems worth trying in other receiver 
designs; you don't get much gain from this sort of RF stage but 
combined with a change to a higher gain mixer it might even be a 
possible 'mod' in a few well-designed and built older sets.

Next up:  The premixer, which (a) did not seem to have enough 
output, and (b) delivered seemingly unnecessary spurious signals 
because it was not balanced to reject the VFO signal.   Yesterday 
I redesigned it to use a 6922 (=6DJ8 but with 300 Ma filament), 
driving the grids from the VFO and the cathodes from a winding on 
the crystal oscillator plate coil.   Both inputs in push-pull and the 
tube plates in parallel so both input signals should cancel out.  

The first problem was that the receiver was dead -- all I got was a 
heck of a lot of noise.  Right ... the 6922 is a VHF tube and I had 
omitted parasitic suppressors.   Adding 100 ohm resistors right at 
each grid connection got things working.   

It does have higher output than the former configuration though I 
have not made measurements yet.   However, it also has even 
more spurious signals.   Most of the new spurs drift and have lots 
of hum; they are all tunable, meaning that the VFO is somehow 
involved.   There are two possibilities:  

1.  They are the result of a VHF parasitic beating with a harmonic 
of one of the oscillators -- most likely the crystal oscillator.   

2.  They are beats between very high harmonics of the VFO and a 
harmonic of the crystal oscillator.  

There's a balance adjustment for the premixer and it greatly 
reduces some of the new spurs but has no effect on others.   It 
could be that this indicates that both types of spur exist or it may 
mean two different paths are being followed for the spur to get into 
the IF.   For example there's obviously the direct path right into the 
grid of the mixer along with the intended premixer output signal.  
(There's only one tuned circuit, so spur attenuation is not that 
great.)   That one would be affected by the balance adjustment.   
But there could also be a radiation path (not enough 
shielding/spacing), a path via the filament circuit, and probably 
others I don't think of that would be unaffected by balance.   

The premixer cathode is 'hot' for RF (both VFO and crystal 
oscillator signals would show up there) so there will be spurious 
signals formed by the heater-to-cathode 'diode.'   

(Because the filament is hot, it forms the 'cathode' of a really 
crummy diode for which the cathode sleeve is the plate.   When 
the cathode sleeve is positive as in the usual cathode bias circuit 
with the filament grounded, a tiny current will flow in that diode.   
That current will be time-varying due to the AC on the filament and 
will be switched by any signal voltage appearing on the cathode 
sleeve.   A perfect (truly lousy) modulated diode mixer ...   The 
cure is to bias the cathode and associated grid returns a few volts 
negative so that the H-K diode never conducts.)

First thing to do is back bias the premixer cathode.  And it 
certainly needs to be separated from the RF stage (which has that 
unbypassed cathode resistor for self-balancing) by a filament 
choke.  

Then more steps as necessary to get rid of the spurs.  There's no 
obvious reason that with a balanced premixer and a high-Q tuned 
circuit in the premixer plate, there should be more than one or two 
faint ones.   

And then, measure performance.  

Walt 
KJ4KV

From bcarling at cfl.rr.com  Sun Nov 21 14:30:26 2004
From: bcarling at cfl.rr.com (Brian Carling)
Date: Sun Nov 21 14:36:25 2004
Subject: [HBR] Homebrewing coils
Message-ID: <41A0A682.22404.20E130C@localhost>

Is it OK to mention on here that I have MDL HI-Q Inductance 
Type "A" PLUG-IN, 4-PIN COILS.
These are some really nice commercially made coils.
Link coupled types, except one as noted...
These look to be brand new RF transformers of exceptional
quality. Note that I only have ONE of each that is shown. 
Available for $8.00 each plus shipping.

See pictures and complete details at:
http://www.af4k.com/coils.htm

Thanks for reading.

From ak0b at swbell.net  Sun Nov 21 17:40:34 2004
From: ak0b at swbell.net (Stan Wilson)
Date: Sun Nov 21 17:47:14 2004
Subject: [HBR] Homebrewing coils
In-Reply-To: <41A0A682.22404.20E130C@localhost>
Message-ID: <000601c4d01b$22678300$0101320a@CPU>

Those are Modern Laboratories coils for Crystal Sets.   I expect I have
an old catalog around here some place.   They will all tune their range
with standard 365 mmf variables.  Stan ak0b

-----Original Message-----
From: hbr-bounces@mailman.qth.net [mailto:hbr-bounces@mailman.qth.net]
On Behalf Of Brian Carling
Sent: Sunday, November 21, 2004 1:30 PM
To: hbr@mailman.qth.net
Subject: [HBR] Homebrewing coils

Is it OK to mention on here that I have MDL HI-Q Inductance 
Type "A" PLUG-IN, 4-PIN COILS.
These are some really nice commercially made coils.
Link coupled types, except one as noted...
These look to be brand new RF transformers of exceptional
quality. Note that I only have ONE of each that is shown. 
Available for $8.00 each plus shipping.

See pictures and complete details at:
http://www.af4k.com/coils.htm

Thanks for reading.

************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
construction notes...... via http://www.qsl.net/k5bcq/ 

Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr

From johnmb at nc.rr.com  Sun Nov 21 18:27:13 2004
From: johnmb at nc.rr.com (john)
Date: Sun Nov 21 18:30:16 2004
Subject: [HBR] Homebrewing coils
In-Reply-To: <000601c4d01b$22678300$0101320a@CPU>
References: <41A0A682.22404.20E130C@localhost>
Message-ID: <3.0.3.32.20041121182713.0200f090@pop-server.nc.rr.com>

I'll mention too, that I have several hundred NOS Meissner
Signal Shifter coil forms, in 4, 5 and 6 pin versions. 

>NOS 4,5 or 6 pin form, Qty 1-10  	$2.25 ea.
>NOS 4, 5 or 6 pin form Qty 11 up 	$2.00 ea.
>NOS Boxed sets of 3 	$9.00 per box

Plus actual shipping cost...

Details at: http://www.old-radios.com/ForSale.html

Thanks!
John K5MO


At 04:40 PM 11/21/04 -0600, Stan Wilson wrote:
>
>Those are Modern Laboratories coils for Crystal Sets.   I expect I have
>an old catalog around here some place.   They will all tune their range
>with standard 365 mmf variables.  Stan ak0b
>
>-----Original Message-----
>From: hbr-bounces@mailman.qth.net [mailto:hbr-bounces@mailman.qth.net]
>On Behalf Of Brian Carling
>Sent: Sunday, November 21, 2004 1:30 PM
>To: hbr@mailman.qth.net
>Subject: [HBR] Homebrewing coils
>
>Is it OK to mention on here that I have MDL HI-Q Inductance 
>Type "A" PLUG-IN, 4-PIN COILS.
>These are some really nice commercially made coils.
>Link coupled types, except one as noted...
>These look to be brand new RF transformers of exceptional
>quality. Note that I only have ONE of each that is shown. 
>Available for $8.00 each plus shipping.
>
>See pictures and complete details at:
>http://www.af4k.com/coils.htm
>
>Thanks for reading.
>
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>construction notes...... via http://www.qsl.net/k5bcq/ 
>
>Retrieve reflector archived data via
>http://mailman.qth.net/mailman/listinfo/hbr
>
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>construction notes...... via http://www.qsl.net/k5bcq/ 
>
>Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
>
>
>
>---
>
>Checked by AVG anti-virus system (http://www.grisoft.com).
>Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
>
-------------- next part --------------

---

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
From bjtatum at ev1.net  Mon Nov 22 20:51:29 2004
From: bjtatum at ev1.net (Byron Tatum)
Date: Mon Nov 22 20:57:31 2004
Subject: [HBR] Homebrewing coils
References: <41A0A682.22404.20E130C@localhost>
	<3.0.3.32.20041121182713.0200f090@pop-server.nc.rr.com>
Message-ID: <008001c4d0fe$f3e8fe20$ade6dacf@your6jnhhu0520>

John-
    I would like to buy 12 of 5 pin and 12 of 6 pin, thanks, Byron.
----- Original Message ----- 
From: "john" <johnmb@nc.rr.com>
To: "HBR Receiver List" <hbr@mailman.qth.net>; <bcarling@cfl.rr.com>; "'HBR 
Receiver List'" <hbr@mailman.qth.net>
Sent: Sunday, November 21, 2004 5:27 PM
Subject: RE: [HBR] Homebrewing coils


> I'll mention too, that I have several hundred NOS Meissner
> Signal Shifter coil forms, in 4, 5 and 6 pin versions.
>
>>NOS 4,5 or 6 pin form, Qty 1-10  $2.25 ea.
>>NOS 4, 5 or 6 pin form Qty 11 up $2.00 ea.
>>NOS Boxed sets of 3 $9.00 per box
>
> Plus actual shipping cost...
>
> Details at: http://www.old-radios.com/ForSale.html
>
> Thanks!
> John K5MO
>
>
> At 04:40 PM 11/21/04 -0600, Stan Wilson wrote:
>>
>>Those are Modern Laboratories coils for Crystal Sets.   I expect I have
>>an old catalog around here some place.   They will all tune their range
>>with standard 365 mmf variables.  Stan ak0b
>>
>>-----Original Message-----
>>From: hbr-bounces@mailman.qth.net [mailto:hbr-bounces@mailman.qth.net]
>>On Behalf Of Brian Carling
>>Sent: Sunday, November 21, 2004 1:30 PM
>>To: hbr@mailman.qth.net
>>Subject: [HBR] Homebrewing coils
>>
>>Is it OK to mention on here that I have MDL HI-Q Inductance
>>Type "A" PLUG-IN, 4-PIN COILS.
>>These are some really nice commercially made coils.
>>Link coupled types, except one as noted...
>>These look to be brand new RF transformers of exceptional
>>quality. Note that I only have ONE of each that is shown.
>>Available for $8.00 each plus shipping.
>>
>>See pictures and complete details at:
>>http://www.af4k.com/coils.htm
>>
>>Thanks for reading.
>>
>>************************************
>>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>>construction notes...... via http://www.qsl.net/k5bcq/
>>
>>Retrieve reflector archived data via
>>http://mailman.qth.net/mailman/listinfo/hbr
>>
>>************************************
>>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>>construction notes...... via http://www.qsl.net/k5bcq/
>>
>>Retrieve reflector archived data via
> http://mailman.qth.net/mailman/listinfo/hbr
>>
>>
>>
>>---
>>
>>Checked by AVG anti-virus system (http://www.grisoft.com).
>>Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
>>
>


--------------------------------------------------------------------------------


>
> ---
>
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
>


--------------------------------------------------------------------------------


> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
>
> Retrieve reflector archived data via 
> http://mailman.qth.net/mailman/listinfo/hbr
>
> 


From windy10605 at juno.com  Mon Nov 22 21:17:25 2004
From: windy10605 at juno.com (windy10605@juno.com)
Date: Mon Nov 22 21:26:51 2004
Subject: [HBR] HBR-13C Receiver
Message-ID: <20041122.201917.932.3.windy10605@juno.com>

This has got to be a record. The nice HBR-13C receiver (looks like the
one in the QST article ?) with the Eddystone 898 dial, went for $776.60.
The HBR-13C was probably the "best looking" version of the HBR series
because of the Eddystone dial. Shows what can happen if you build a
really nice looking HBR Receiver and there are others wanting one. The
seller in Canada said he was the builder.    

73 Kees K5BCQ
From johnmb at nc.rr.com  Tue Nov 23 06:46:22 2004
From: johnmb at nc.rr.com (john)
Date: Tue Nov 23 06:48:27 2004
Subject: [HBR] Homebrewing coils
In-Reply-To: <008001c4d0fe$f3e8fe20$ade6dacf@your6jnhhu0520>
References: <41A0A682.22404.20E130C@localhost>
	<3.0.3.32.20041121182713.0200f090@pop-server.nc.rr.com>
Message-ID: <3.0.3.32.20041123064622.01fecf04@pop-server.nc.rr.com>

Hi Byron,
I'll get them out for you. Please send your address for me to 
estimate shipping.
Thanks!
John


At 07:51 PM 11/22/04 -0600, you wrote:
>
>John-
>    I would like to buy 12 of 5 pin and 12 of 6 pin, thanks, Byron.
>----- Original Message ----- 
>From: "john" <johnmb@nc.rr.com>
>To: "HBR Receiver List" <hbr@mailman.qth.net>; <bcarling@cfl.rr.com>; "'HBR 
>Receiver List'" <hbr@mailman.qth.net>
>Sent: Sunday, November 21, 2004 5:27 PM
>Subject: RE: [HBR] Homebrewing coils
>
>
>> I'll mention too, that I have several hundred NOS Meissner
>> Signal Shifter coil forms, in 4, 5 and 6 pin versions.
>>
>>>NOS 4,5 or 6 pin form, Qty 1-10  $2.25 ea.
>>>NOS 4, 5 or 6 pin form Qty 11 up $2.00 ea.
>>>NOS Boxed sets of 3 $9.00 per box
>>
>> Plus actual shipping cost...
>>
>> Details at: http://www.old-radios.com/ForSale.html
>>
>> Thanks!
>> John K5MO
>>
>>
>> At 04:40 PM 11/21/04 -0600, Stan Wilson wrote:
>>>
>>>Those are Modern Laboratories coils for Crystal Sets.   I expect I have
>>>an old catalog around here some place.   They will all tune their range
>>>with standard 365 mmf variables.  Stan ak0b
>>>
>>>-----Original Message-----
>>>From: hbr-bounces@mailman.qth.net [mailto:hbr-bounces@mailman.qth.net]
>>>On Behalf Of Brian Carling
>>>Sent: Sunday, November 21, 2004 1:30 PM
>>>To: hbr@mailman.qth.net
>>>Subject: [HBR] Homebrewing coils
>>>
>>>Is it OK to mention on here that I have MDL HI-Q Inductance
>>>Type "A" PLUG-IN, 4-PIN COILS.
>>>These are some really nice commercially made coils.
>>>Link coupled types, except one as noted...
>>>These look to be brand new RF transformers of exceptional
>>>quality. Note that I only have ONE of each that is shown.
>>>Available for $8.00 each plus shipping.
>>>
>>>See pictures and complete details at:
>>>http://www.af4k.com/coils.htm
>>>
>>>Thanks for reading.
>>>
>>>************************************
>>>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>>>construction notes...... via http://www.qsl.net/k5bcq/
>>>
>>>Retrieve reflector archived data via
>>>http://mailman.qth.net/mailman/listinfo/hbr
>>>
>>>************************************
>>>Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>>>construction notes...... via http://www.qsl.net/k5bcq/
>>>
>>>Retrieve reflector archived data via
>> http://mailman.qth.net/mailman/listinfo/hbr
>>>
>>>
>>>
>>>---
>>>
>>>Checked by AVG anti-virus system (http://www.grisoft.com).
>>>Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
>>>
>>
>
>
>---------------------------------------------------------------------------
-----
>
>
>>
>> ---
>>
>> Checked by AVG anti-virus system (http://www.grisoft.com).
>> Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
>>
>
>
>---------------------------------------------------------------------------
-----
>
>
>> ************************************
>> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
>> construction notes...... via http://www.qsl.net/k5bcq/
>>
>> Retrieve reflector archived data via 
>> http://mailman.qth.net/mailman/listinfo/hbr
>>
>> 
>
>
>************************************
>Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
>construction notes...... via http://www.qsl.net/k5bcq/ 
>
>Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr
>
>
>
>---
>
>Checked by AVG anti-virus system (http://www.grisoft.com).
>Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
>
-------------- next part --------------

---

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04
From waltah at earthlink.net  Thu Nov 25 11:51:40 2004
From: waltah at earthlink.net (waltah@earthlink.net)
Date: Thu Nov 25 11:59:30 2004
Subject: [HBR] Another Receiver Project -- HBR-4, Part 22
In-Reply-To: <41A08DC1.29619.EF9650@localhost>
References: <419DFF6F.795.1239422@localhost>
Message-ID: <41A5C74C.30800.6F3D0E@localhost>

'Makin' progress.'

Sure enough back biasing the premixer cathode eliminated the 
wierd unstable spurs.   However there were still some S9+30 nice 
stable spurs, particularly the one at 3600 Kcs which is the 5th 
harmonic of the VFO at 5.4 = 27 Mcs less the crystal frequency of 
18 yielding 9 Mcs.

The first question was whether the VFO drive to the premixer was 
too high.  Cutting the VFO plate voltage in half cost only a few db 
of signal strength but reduced the 3600 kcs spur from S9+30 to 
about S5.   The next step took some poking around, but what I did 
eventually was run the 2" lead from the premixer plate to G1 of the 
6JH8 mixer using RG-174/U coax.   That got it down around S1.  
Then I tweaked the mixer balance pot and was able to make it 
nearly vanish -- you can hear it, but the S-meter doesn't move.

In hindsight this should have been much easier to see:  All the 
serious spurs are 9 Mcs signals coming out of the premixer.  
However going into the mixer G1 with output from that tube taken in 
in push pull from the plates, such signals should vanish.   If they 
don't, then either you have a shielding problem -- the signal is 
leaking more to one plate than the other -- or you have a balance 
problem.  I had both.

There's still a just-audible response to very strong signals on 80 
and 20 meters caused by direct conversion (no crystal frequency) 
using the 5-5.5 Mcs VFO a la 'band imaging.'    Jiggering the 
crystal and VFO frequencies would solve this (in a repeat project) 
by moving these responses far enough from the proper one for front 
end attenuation to take them out.   However, impurity of the LO 
signal is nasty, regardless.   Since the lowest frequency out of the 
premixer should be 14 Mcs above the band, I'm going to try a high-
pass filter at the premixer output.

I'll probably do some further investigation of the shielding issues in 
that area.   And then probably increase the VFO plate voltage a 
little to recover the lost gain.   The VFO power level is fine -- ~100 
mW plate input.

I haven't noticed any other spurs but I haven't looked carefully yet.

Meanwhile I noticed that the front end peaked up at quite different 
settings compared to the time before 'it thinks it's push-pull.'   A 
little study showed that I had incorrectly arranged the new winding 
on the RF to mixer transformer, putting it at the hot end of the 
existing winding rather than the cold one. Figuring that that had 
increased the stray capacitance, I did it again, (right this time) and 
adding one more turn.   The bad news is that even with things laid 
out correctly, the tuning is still quite different, making the front 
panel markings wrong and probably hurting the gain on 10 meters.  
However the good news is that I was able to get plenty of gain by 
taking output from the plates of the push pull RF stage directly to 
the deflection plates of the 6JH8. 

I can't prove that that makes anything better, but it's a lot more 
esthetically satisfying.   The receiver does sound teriffic in that 
configuration.

I'll have to further investigate capacitance issues in that stage.  The 
main problem is likely to be the combination of the 6ES8 (RF 
stage) plates and the 6JH8 (mixer) deflection plates, but it's too 
soon to say for sure. The wiring of the bandswitch can certainly be 
improved.   And a trick or two may be possible. 

The one remaining major problem area is the crystal oscillator.   It's 
unstable, hard to tune up ... I think that covers it.   Further work is 
needed there -- those crystals should be 'rock solid.'   I don't think 
it's an excessive drive situation; more likely just that the Q of the 
tank is too high.   But loading that is kind of a mess and I've been 
resistant to getting serious about it.   There's ample gain available --
I'm running that tube at about 60 volts and getting plenty of output.

And a lesser problem -- there's still too much 9 Mcs leakage from 
the antenna.  I have a trap there, but more is needed.   

The shape of the bandpass is not quite the same for strong signals 
as it is for weak ones, indicating some IF regeneration.  

Walt
KJ4KV


From lmilford at usadatanet.net  Sun Nov 28 18:23:52 2004
From: lmilford at usadatanet.net (Les Milford)
Date: Sun Nov 28 18:31:06 2004
Subject: [HBR] Looking for Ballentine 9648M Manual AN / USM 326A
Message-ID: <001601c4d5a1$5386a340$37ea4345@g8u4o6>

Hello,
I am looking for a manual or copy of a manual for a Ballantine 9648M (Mfg. P/N) or AN / USM 326A counter. I have spent MANY hours looking on the net, and just found one available from Ballantine. However, it pains me greatly to have to part with 100 clams for it. Does anyone have this or know where I can get it at a much lower cost? Any info would be greatly appreciated.Thank You.
Les KB2KNX lmilford@usadatanet.net
From wnichelson at snip.net  Sun Nov 28 21:16:34 2004
From: wnichelson at snip.net (William N)
Date: Sun Nov 28 21:24:27 2004
Subject: [HBR] Looking for Ballentine 9648M Manual AN / USM 326A
References: <001601c4d5a1$5386a340$37ea4345@g8u4o6>
Message-ID: <000701c4d5b9$73ddfa90$5b5bccd1@Bill>

Hi Les,
Try http://www.agtannenbaum.com/
Good Luck & 73
Bill W3 KOC

----- Original Message ----- 
From: "Les Milford" <lmilford@usadatanet.net>
To: <hbr@mailman.qth.net>
Sent: Sunday, November 28, 2004 6:23 PM
Subject: [HBR] Looking for Ballentine 9648M Manual AN / USM 326A


Hello,
I am looking for a manual or copy of a manual for a Ballantine 9648M (Mfg.
P/N) or AN / USM 326A counter. I have spent MANY hours looking on the net,
and just found one available from Ballantine. However, it pains me greatly
to have to part with 100 clams for it. Does anyone have this or know where I
can get it at a much lower cost? Any info would be greatly appreciated.Thank
You.
Les KB2KNX lmilford@usadatanet.net
************************************
Visit the HBR Receiver Web Site with over 100 pictures of receivers and
construction notes...... via http://www.qsl.net/k5bcq/

Retrieve reflector archived data via
http://mailman.qth.net/mailman/listinfo/hbr





From gswynar at durham.net  Tue Nov 30 13:52:47 2004
From: gswynar at durham.net (Ed Swynar)
Date: Tue Nov 30 14:00:35 2004
Subject: [HBR] Testing The 1929 Rig...
Message-ID: <019101c4d70d$cd41ba40$c4d549c6@CompaqS5000>

Greetings You Purveyors of the Past Perfect,

I am pleased to announce that I will FINALLY be able to commence testing the 1929 set-up here as of TO-NIGHT (Tuesday), in preparation for the upcoming Antique Wireless Association Bruce Kelley Memorial 1929 QSO Party...

Do please have a listen for me in the next little while---in the evenings I should be on between 3550- and 3580-KHz...in the day time, look for me between 7030- and 7050-KHz. I'll commence running just the 3 x 227 MOPA, eventually graduating (hopefully) to this rig driving a pair of parallel 245's.

In any event, I'll be none too powerful---but the signal should still be a stand-out(!), if you know what I mean...

Give me a shout if you're able to copy, or at least report back via the internet on what you've heard.

Many thanks...and BTW, are YOU ready for the upcoming event...?!

~73~ Eddy VE3CUI - VE3XZ
