From hbr@mailman.qth.net  Sat May 10 02:44:19 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Fri, 9 May 2003 21:44:19 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
In-Reply-To: <3EAC1F64.53.2BC50AF@localhost>
References: <3E98180E.4396.E59187@localhost>
Message-ID: <3EBC2133.3374.2B89258@localhost>

(In the previous part I got the IFDR up to about 70 db at the antenna 
and considered the choice between working on the mixers to try to 
carry the 84 db IFDR number at the filter driver back to the antenna 
and going the other way to improve the 84 db number by reducing the 
noise at the 1st IF stage.)

I didn't wanna do it, but in the end the 1st IF stage changes won.   
There was just too much wrong there.  The need for high gain 
seemed to give me inescapable problems with pickup of stray 
signals (3180 kcs IF = 2x 1590 = 3x 1060 ...) and subtle feedback 
issues.   Even if it could be tamed, a 'touchy' stage has no place in a 
design others might try to duplicate.   

I ripped out the tuned circuit and as a first step wound a 4:1 (bifilar) 
transformer to couple the filter to the cathode of the 6EH7 1st fixed IF 
stage.   It worked (and didn't work) in exactly the way you might 
suppose: All the weirdness was gone and such signals as I could 
hear, sounded very clean.   However the gain was way too low and 
the receiver noise was now dominated by  that stage.   The gain 
might be somewhat improved by a better match from filter to cathode 
-- 500 ohms to an 80 ohm (about) cathode isn't 4:1 -- but the problem 
was larger than that.

Next stop a grounded-grid triode stage -- or rather, two G-G stages (a 
6ES8).   Matching a 500 ohm filter to a nominal 80 ohm cathode 
(1/12,500 uMhos) 6ES8 cathode called for tapping a 30 turn toroid at 
12 turns. But the filter passband wasn't quite the right shape, 
indicating a mismatch.   Digging further I discovered what I might 
have calculated at the start: my untuned transformer didn't have 
enough inductance to work right at 3180 Kcs.   In the audio world 
you'd say the transformer didn't have enough 'low end.'    The easy 
answer was to tune it and doing so allowed me to do the impedance 
match by adjusting the ratio of two capacitors in series rather than 
by adjusting the tap on a coil -- a bunch simpler for testing and 
simpler to duplicate, as well.

The overall gain was better but still too low.  I increased the gain of 
the 2nd IF to the maximum and boosted the RF stage slightly: still 
not enough.   

Reluctantly, I decided to try to feed the stage at the grid, giving a 
genuine cascode setup.  In the process, I learned another one of 
those obvious facts -- for any given unneutralized amplifier tube there 
is an input impedance above which it will oscillate.  Getting the 
correct ratio to step up 500 ohms to the grid with no trace of 
regeneration with the tube operating at the desired (near maximum) 
gain took about two weeks and maybe a dozen tries?   But it was 
worth it -- perfect clean signals, rock solid stability, a nice, flat filter 
passband, no pickup of stray sigs.   And there was now plenty of 
gain.  

(Lowering the grid impedance from 33 to 12k helped cut the stray 
pickup but the main thing was probably that with the resulting lower 
Q I was able to eliminate the trimmer cap, and so cut the total lead 
length in the grid circuit severalfold.)

Unfortunately ... the final measurements at the filter driver were noise 
floor 107dbm, IP3, 19.5 dbm,  and IFDR 84.5 db -- not significantly 
better numbers than before.   

Since the distortion that set the IP3 was presumably in the filters 
themselves, better sensitivity had to mean a better IFDR.   And the 
improved function said the measurements should be better.   
Something was wrong ...

Fortunately, my course in Receiver Design Self Taught In Only A 
Few Dozen Long Exasperating Lessons had now equipped me to 
deal with this. I had to push the URM-25 signal generators pretty 
hard to test this stage; could they (again) be the problem?   I 
repeated the IP3 measurement at two lower signal levels; by the 
theory, IP3 does not depend on the level at which the measurement 
is done but I got three very different answers.   Since the answer got 
better with increasing test power levels, the conclusion was that 
there was indeed distortion in the signal generators.   

The good news is that measuring at successively higher levels gives 
results that approach the right answer.   So the section from the filter 
driver on has an IP3 of better than 19.5 dbm and an IFDR better than 
84.5 db.   That's good enough for now.   

(A way to think of this:  The signal generators operate at constant 
conditions, hence the strength of the false signals from distortion 
there is a constant fraction of their output.   Changing the attenuation 
ahead of the receiver subjects it to a varying input; its 3rd-order 
distortion changes at three times the rate at which the input 
changes.  At a sufficiently high input, the receiver distortion swamps 
the false signal from the generator so the measured IP3 approaches 
the correct answer.)

What next?   The overall receiver gain is about right as indicated by 
S9 (i.e., AGC voltage about half cutoff for the controlled stages) being 
close to 50 uV.   But the noise floor measuring at the antenna is 
around -116 dBm (0.23 uV would be -120 dBm) -- that's marginal at 
best.  And a 70 dB IFDR at the antenna probably means that one or 
both mixers enter distortion before the filters do.  Since the noise is 
now mainly from the mixers, the performance probably can be 
improved just by reducing the mixer gain and increasing the gain of 
the RF stage.

Sounds so simple, doesn't it?

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Sat May 10 07:43:39 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Sat, 10 May 2003 02:43:39 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
References: <3E98180E.4396.E59187@localhost> <3EBC2133.3374.2B89258@localhost>
Message-ID: <01cb01c316bf$7dfa0dd0$0500a8c0@eoz>

Walt -

Hate to be the "Devil's Advocate" here, And, posssibly you answered this in
a previous post. In either case, could you please remind of the bandwidth
that you are using to measure your noise floor? Thanks & 73 - Mike



Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193





From hbr@mailman.qth.net  Sat May 10 17:33:27 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sat, 10 May 2003 12:33:27 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
In-Reply-To: <01cb01c316bf$7dfa0dd0$0500a8c0@eoz>
Message-ID: <3EBCF197.881.84DDEF@localhost>

Mike Feher wrote:
> Hate to be the "Devil's Advocate" here, And, posssibly you answered this
> in a previous post. In either case, could you please remind of the
> bandwidth that you are using to measure your noise floor?

A lot of the reason for posting all that stuff is to get other thoughts 
and viewpoints.   If I knew what I was doing, I'd have finished the 
project six months ago.    Since this is in large measure a learning 
experience, please advocate!   

I measure the NF in the time-honored ham way -- with an AC 
voltmeter on the audio output; actually, across the primary of the 
output transformer.   I set the audio gain for a convenient reading on 
noise alone -- say 1 volt -- then apply the signal and adjust it for triple 
the reading -- 3 volts in this case.   That would be roughly a 10 db 
ratio of (signal+noise)/noise.   

So the measurement bandwidth is set mainly by the audio bandwidth 
-- probably 5 kcs or so -- and the bandwidth of the filter in use, 
usually 2.4kcs.  

Such a casual approach can cause a few db error when comparing to 
measurements made on other sets and would show the HBR2K 
unfavorably if the other set measurement was made with a narrower 
bandwidth;  the effect would be 3 db/doubling, right?  Measuring at 
4kcs would make the NF 6 db higher (worse) than measuring at 1 
kcs bandwidth.

Of course my noise isn't uniformly distributed over the 4kcs -- there's 
more in the 2.4kcs corresponding to voice intelligence because most 
noise (now) actually comes from the mixers and must get through 
the filter. Only the 3180kcs IF noise (generated after that filter) is 
broadband enough to cover the audio section bandpass in a uniform 
fashion.   

(In very high quality receivers it is common to include a second 
selective filter at the end of the IF chain right ahead of the detector to 
take out the out-of-bandwidth IF generated noise but the added 
complication didn't seem worthwhile for this project.)

I think the method is good enough for measuring my progress.   And 
the absolute answer it gives squares with my subjective impression -- 
this receiver is 'getting there' but it is still too noisy.   I expect that 
when a really good set is adjusted to comfortably receive signals on 
even a fairly quiet band (say, 20 when things are good -- does 
anyone remember the last time that happened?) if you then 
disconnect the antenna, the set goes essentially silent -- you might 
not know it was on.   HBR2K at its current state gets considerably 
quieter, but no one would yet call it 'silent.'    

Walt Hutchens
KJ4KV





From hbr@mailman.qth.net  Sat May 10 23:07:54 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sat, 10 May 2003 18:07:54 EDT
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
Message-ID: <134.1f94e418.2beed23a@aol.com>

Just a quick note.....

I'm beginning to wonder if the performance of the HBR2K is actually much 
better than the test setup permits to be shown? I recall the comment in a 
receiver article many, many years ago (I think it was the "75 Meter Receiver 
For DX Work" by W1KLK, QST about 1972) where the author noted that in order 
to build a better receiver, it would be necessary to first build better test 
gear because his lab-quality signal generator put out only 0.1 volt, which 
wasn't near enough to cause overload in his rx.

73 de Jim, N2EY

From hbr@mailman.qth.net  Sun May 11 03:11:20 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sat, 10 May 2003 22:11:20 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
In-Reply-To: <134.1f94e418.2beed23a@aol.com>
Message-ID: <3EBD7908.9255.2960346@localhost>

Jim, N2EY:
> I'm beginning to wonder if the performance of the HBR2K is actually much
> better than the test setup permits to be shown?

I think I have a pretty good handle on this now, although I have had a 
remarkably hard time learning that I have to deal with it each and 
every time I make a measurement.

The short answer (which won't, of course, satisfy me) is that some of 
HBR2K's performance is indeed better than I can measure.   (The 
performance at the filter driver may be significantly better than 84.5 
db IFDR the measurements give.)   However, there are work-arounds 
that will let progress continue, I may be able to lift the measurement 
limits, and in any case I expect to be able to correctly measure the 
end result.

And the longer answer ...

After some study I have concluded that the URM-25's are pretty 
decent signal generators for this job, because:

1.  They're *powerful* -- the oscillator (tube type varies from one 
model to another) drives a 6AH6 buffer which drives a 6AG7 output 
stage.   Yeah, that's not a typo -- the output tube would work fine in a 
10 watt class transmitter.   The 'final' stage output is around 2 volts 
RMS (they're not exactly pushing it hard); at the built-in attenuator 
there's about 0.1 volts RMS.  

2.  They have pretty good isolation -- there's a 20 db fixed pad 
between the output tube and the attenuator and there's nothing that 
could be non-linear after that pad.

3.  They have no ALC to cause crossmodulation when power from 
the other generator comes in at the output port.

Now just like the QST author, I'm limited by the maximum output, but 
either his receiver was considerably better than mine -- okay, so I 
hereby commit to finding that article -- or he was testing by pushing 
his into compression rather than measuring IP3.  The measurements 
are equivalent for comparing receivers (a good compression limit or a 
good IP3 is equally descriptive of a good strong signal receiver) and 
IP3 can be measured at lower power levels -- I am now doing it at 13 
db below the 100,000 uV maximum output, or something like 20,000 
uV.

And I am also doing two measurements at different power levels 
whenever I want a serious number.   If the result at the higher level is 
better than the one at the lower level then generator (or hybrid 
combiner) distortion is limiting and the high power number is a lower 
limit for the actual performance.   

FWIW, I'm finding that just as was the case at the filter driver, the 
test setup is limiting at the 2nd mixer.  That's not a serious problem 
for same-power level 'is this modification an improvement' tests but 
does mean that absolute numbers are not meaningful.   

And the numbers at the antenna *are* trustworthy -- that is, at 
various test power levels I get the same IP3, as the theory says I 
should.   Combining that with the noise floor measured at that point, I 
get a trustworthy but less-than-satisfactory 70-72 IFDR.   And my 
guess is that when the mixer optimization is done (not necessarily 
just tweaking resistors -- I may have to redesign the 1st oscillator!) 
and (after that) when the RF stage is tweaked,  I'll be also able to 
measure the final number at the antenna in a trustworthy fashion.

The reason I say that is that the adequacy of the test setup is a 
function of how much signal it has to furnish -- smaller test demands 
are more easily supplied.  As I get closer to the antenna, that 
number goes down.

In the next few days I'll test my combiner, which is the *handbook* 
device.   (Should be easy  -- just compare third harmonic output from 
the combiner vs. a 6 db attenuator, using a general coverage 
receiver.)    If it's not good I'll either improve it or look for a 
commercial combiner.  

Also, it ought to be possible to calculate the correct value of IP3, 
given two or more of the incorrect values.    

Again, I commend the comments by John Thorpe, designer of the 
AOR 7030, at:

http://www.aoruk.com/comments.htm

This is not a mathematical treatment nor in any way unreadable for a 
ham who works on receivers and has thought some about theory; 
heck, it's even fun reading -- he has a great sense of humor.   But it's 
the soundest and clearest exposition of methods and issues in 
strong-signal testing of high performance receivers that I've seen -- 
far, far more useful than the stuff in our *Handbook*.

And a final word (again) about why this long strong-signal exercise is 
worthwhile.   Way back at the start I picked the target of showing 
that far better receivers *could* have been built at the end of the 
vacuum tube era than ever *were* produced -- basically, I believe that 
for marketing reasons manufacturers jumped for the solid state 
bandwagon while square wheels were still the solid state of the art.   
Beating the usual 1970 receiver's stability and audio quality has been 
easy to do.  But the real test of a receiver is 'what can you hear when 
the going gets rough' and that is largely determined by internal noise 
and intermodulation distortion.  

This phase has been slow going because I've been able to copy very 
little circuitry intact and have had to learn most of the 'how to' from 
near the beginning.   I believe it would have been a straightforward 
exercise for a good professional in 1970 -- say as a development 
contract for an R-390B or an Art Collins demand for a 75S4.   And 
the commercial/military and/or ham world would have then had the 
choice of a receiver that would not have been bested by the solid 
state sets for 10-15 years -- I don't know exactly. 

Thanks for the comments Jim, Mike, others -- they are appreciated.  
I often clarify my thinking or get ideas while reading or trying to 
answer.  

Back to the bench -- actually, the kitchen counter.

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Sun May 11 17:59:23 2003
From: hbr@mailman.qth.net (Niel Wiegand)
Date: Sun, 11 May 2003 11:59:23 -0500
Subject: [HBR] Front Panel Lettering?
Message-ID: <3EBE816B.8D88DD90@arrl.net>

I recently acquired a restoration project (see:
http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).

I'm going to have to redo the front panel. Any suggestions for the
lettering? Is there any material available that I can run through my
computer printer to make my own labels?

73, 
Niel - W0VLZ
http://www.io.com/~nielw/wa5vlz.htm


From hbr@mailman.qth.net  Sun May 11 18:58:09 2003
From: hbr@mailman.qth.net (fkamp)
Date: Sun, 11 May 2003 12:58:09 -0500
Subject: [HBR] Front Panel Lettering?
References: <3EBE816B.8D88DD90@arrl.net>
Message-ID: <3EBE8F31.B7B9FFC0@attbi.com>

Yes, indeed.  In the past I have made my own decals using the toner transfer method
of making printed circuit boards.  You need a special paper and a laser printer to
make it work.

Normally you print out circuit traces onto the paper.  Then reactivate the toner
with a clothes iron to transfer the toner to the copper. Then soak the whole thing
in water to make the paper release from the toner.

To make decals, you print out your artwork.  Then spray it with clear krylon or some
other spray on laquer.  When the laquer dries, you float the paper in water and the
decals release from the paper.  Works just like those decals I used to use on model
airplanes.

Do a search for dry toner transfer on the internet to see where you can get the
paper.  I have also used high gloss ink jet paper.  It works too, but I have not
tried it for making decals.  It is cheaper but if you only need a couple of sheets
the price difference is not worth the hassle.

Regards,
Frank Kamp


Niel Wiegand wrote:

> I recently acquired a restoration project (see:
> http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).
>
> I'm going to have to redo the front panel. Any suggestions for the
> lettering? Is there any material available that I can run through my
> computer printer to make my own labels?
>
> 73,
> Niel - W0VLZ
> http://www.io.com/~nielw/wa5vlz.htm
>
> ************************************
> 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 hbr@mailman.qth.net  Sun May 11 20:02:27 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sun, 11 May 2003 15:02:27 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
In-Reply-To: <3EBD7908.9255.2960346@localhost>
References: <134.1f94e418.2beed23a@aol.com>
Message-ID: <3EBE6603.9387.17D9ABE@localhost>

> In the next few days I'll test my combiner, which is the *handbook* 
> device.   (Should be easy  -- just compare third harmonic output from the
> combiner vs. a 6 db attenuator, using a general coverage receiver.)    If
> it's not good I'll either improve it or look for a commercial combiner. 

"It's the combiner, stupid" -- or so it seems.

I couldn't, of course do the proposed third harmonic test because the 
signal generators have tons of third harmonic energy.  But I set the 
generators to 3.5 and 6.5 Mcs and ran them through the combiner to 
the receiver, tuning it to 10 Mcs.   Wow ... at full generator output of 
100,000 uV with 28 db of attenuation after the combiner, I had an S-9 
distortion signal at 10 Mcs.   Adding 20 db attenuation to each 
generator *ahead* of the combiner dropped the signal nearly to 
inaudibility, even with *no* attenuation after the combiner.   So the 
thing is wildly non-linear at power levels below +6dbm.   

Where's the bag of toroids?   By stacking cores I had in twenty 
minutes a bifilar transformer with 2-1/2 times the core area and in a 
couple minutes more, a combiner that is 27 db cleaner at 100,000 
uV, giving an S9 distortion signal with 1 db of post-combiner 
attenuation, rather than 28 db.   *That* should make better 
measurements possible ... we'll see.  

I'll order some larger cores later today; it ought to be possible to 
make a combiner that will handle the full generator output with little 
or no non-linearity.   The price will be high end performance -- the 
*Handbook* design I was using is supposed to be okay to around 50 
Mcs and with more distributed capacitance a high power unit 
probably won't get there.   But then, I don't *want* to go there.

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Sun May 11 22:13:06 2003
From: hbr@mailman.qth.net (Jeff Noel)
Date: Sun, 11 May 2003 17:13:06 -0400
Subject: [HBR] Re: [HBR]
References: <3EBE816B.8D88DD90@arrl.net>
Message-ID: <000e01c31802$1eb6bf00$356d2c42@hppav>

Niel,

You have a great web site. I checked out the old regen radios.

Jeff


From hbr@mailman.qth.net  Mon May 12 00:05:06 2003
From: hbr@mailman.qth.net (Mobile Engineering)
Date: Sun, 11 May 2003 18:05:06 -0500
Subject: [HBR] Front Panel Lettering?
In-Reply-To: <3EBE816B.8D88DD90@arrl.net>
Message-ID: <5.2.1.1.2.20030511175654.00b36df0@pop.mnic.net>

Niel,

Curious that you should ask! I'm sweating through the same problem/solution 
on my HBR-16 at this time. The Dymo labels I've had in place since getting 
the HBR functioning 33 years ago have outlived their usefulness...esp. in 
light of my just designing/building/assembling/adding a new slide-rule dial 
to replace the old tough-torque 180-degree National (MCN?).

I'm tinkering with trying a combination of Leroy lettering - in white paint 
if I can make the Leroy pens handle it - and maybe try my hand at actually 
engraving plastic labels. (Got a commercial quote of $250 for the engraving 
which nixed the commercial solution.)

As for the dial, I've calibrated strips of paper for each band using a 
0.7mm pencil - guiding on the edge of the slide rule pointer - and a friend 
is attempting to scan in and enhance my crude lines and also do the 
lettering. Just today he told me he's tinkering with it and is getting more 
familiar with a new program to do so. But he hopes I'm not too impatient 
for a quick turnaround!

73's,

John, K0YQX

At 11:59 AM 5/11/2003 -0500, you wrote:
>I recently acquired a restoration project (see:
>http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).
>
>I'm going to have to redo the front panel. Any suggestions for the
>lettering? Is there any material available that I can run through my
>computer printer to make my own labels?
>
>73,
>Niel - W0VLZ
>http://www.io.com/~nielw/wa5vlz.htm
>
>************************************
>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 hbr@mailman.qth.net  Mon May 12 01:41:48 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Sun, 11 May 2003 19:41:48 -0500
Subject: [HBR] Front Panel Lettering?
Message-ID: <20030511.194204.-229717.2.windy10605@juno.com>

Darrell had a great idea for lettering using a Brother P-touch
label maker. They are around $30 and have black on clear, white 
on clear, etc tapes available. Just print up the label with whatever 
you want, trim it to the size of the word, remove the backing 
and stick it on. Use a X-acto blade to separate the backing.

73 Kees K5BCQ 

From hbr@mailman.qth.net  Sun May 11 12:21:46 2003
From: hbr@mailman.qth.net (Helmut Usbeck)
Date: Sun, 11 May 2003 07:21:46 -0400 (Eastern Daylight Time)
Subject: [HBR] Front Panel Lettering?
In-Reply-To: <3EBE816B.8D88DD90@arrl.net>
References: <3EBE816B.8D88DD90@arrl.net>
Message-ID: <Pine.WNT.4.53.0305110714380.-151765@laptop>

Yes, hobby shops which cater to RR and mdel airplane buffs carry
several types a "decal" paper.  Works best with H-P and Epson printer
types and inks.  Canon bubble printers don,t work.

Regards,
Helm.  WB2ADT  [K2, 2698]


On Sun, 11 May 2003, Niel Wiegand wrote:

> I recently acquired a restoration project (see:
> http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).
>
> I'm going to have to redo the front panel. Any suggestions for the
> lettering? Is there any material available that I can run through my
> computer printer to make my own labels?
>
> 73,
> Niel - W0VLZ
> http://www.io.com/~nielw/wa5vlz.htm
>
> ************************************
> 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 hbr@mailman.qth.net  Mon May 12 14:06:41 2003
From: hbr@mailman.qth.net (David Newman W3HYM)
Date: Mon, 12 May 2003 09:06:41 -0400
Subject: [HBR] Front Panel Lettering?
References: <3EBE816B.8D88DD90@arrl.net>
Message-ID: <3EBF9C61.44EDD264@OLG.com>

I have used decal sheets from Micromart, with  Color Laser printer.  Excellent
results
for lettering.  Only problem, cannot  print white.  So I painted my panels for KW
amplifier BABY BLUE.  The BABY BLUE paint I obtained from an auto supply store.
First
prime then paint.  I then used black lettering on the light blue.  Also, I made some

fancier lettering with my callsign in red.  All looks good on the light blue.

I strongly recommend using laser decal paper, with laser printer.  Will work with
laser
printer that prints black (normal laser printer).  You must get a preservative
solution
to put on laser printer after you print the lettering.  Otherwise, lettering will
come
off in water.  Micromart has a kit with all the necessary solutions, for about $16
or
$17.

Good luck!

David
W3HYM

Niel Wiegand wrote:

> I recently acquired a restoration project (see:
> http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).
>
> I'm going to have to redo the front panel. Any suggestions for the
> lettering? Is there any material available that I can run through my
> computer printer to make my own labels?
>
> 73,
> Niel - W0VLZ
> http://www.io.com/~nielw/wa5vlz.htm
>
> ************************************
> 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 hbr@mailman.qth.net  Mon May 12 19:31:23 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Mon, 12 May 2003 14:31:23 -0400
Subject: [HBR] Front Panel Lettering?
In-Reply-To: <3EBF9C61.44EDD264@OLG.com>
Message-ID: <3EBFB03B.20382.11C3C10@localhost>

Decal printer paper is also available on the web; just hit Google with 
'decal paper printer' and follow the trail.   

The inks used in jet printers fade rather badly when exposed to even 
indirect sunlight, so unless you keep the windows covered, a panel 
done with inkjet decals may have a short life.   The black laser printer 
inks (toner) appears to be carbon-based and will last indefinitely.

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Mon May 12 20:46:32 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Mon, 12 May 2003 15:46:32 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
References: <3EBCF197.881.84DDEF@localhost>
Message-ID: <005f01c318bf$308a8370$0500a8c0@eoz>

Walt -

I apologize, but I somehow missed your response to my question. No doubt
about it, you are learning a lot as you go along and helping the rest of us
as well. There are, however, from my perspective, a few flaws in your
calculations and I will attempt to see if I can clarify them. With regards
to the noise floor that determines SNR, of course what you get at the
antenna terminals is the best SNR you will have. Every stage after that will
degrade it. I am sure you have by now run across the formulas that determine
the NF degradation through each stage as a function of individual stage NF
and gain. Obviously, the most offending stage is typically the mixer, as it
has the least gain. The front end does help this out substantially, but, in
the process it also generates noise, so, in reality the ultimate noise floor
cannot be achieved. What is the ultimate noise floor one may ask. Well under
well matched antenna and receiver terminations and at room temperature of
290 degrees Kelvin, it is -173 dBm/Hz. Or, simply kT, where k is Boltzman's
constant and T is the temperature. Often you see it represented in total
power, as kTB, where B is the bandwidth of the receiving system prior to
going to the detector. The receiver has so much gain in the early stages
that the latter ones barely contribute to noise at all, and especially, the
audio amp can be ignored. The real important thing as I mentioned before is
what hits the detector, which is your decision making circuit. So, B is
typically defined by the IF bandwidth, however, it is not as simple as that.
For example if you did not have a selective front end, well then you would
also encounter "image noise" and the noise floor to start with could be 3 dB
higher than anticipated as the image noise now also passes through the
receiver. Ideally, your noise bandwidth would be determined by your IF
bandwidth, if your IF filter had a perfect transition region from the
passband to the stopband of the filter. In reality, that also is not
achievable, so while your "X" dB bandwidth may be 2.4 kHz, the actual noise
bandwidth is somewhat wider and can be easily figured out by integrating the
area of the filter's response. OK, I am going on again so let's get to the
point. Let's assume that your IF is equivalent to 3 KHz prior to allowing
the signals to get to the detector. So, what is kTB for 3KHz? Well it is
simply the -173 dBm/Hz plus 10 times the log of 3000, or, about -138 dBm.
You claim that your receiver's noise floor is -107 dBm, or, 31 dB lower than
ideal, utilizing your filter. This implies that your receiver's NF (noise
figure) is 31 dB. Does that make sense? I would be surprised if it was over
15 dB. So, to me, right now things just do not add up. Hope every one is
still awake. 73 - Mike



Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193



----- Original Message -----
From: <waltah@earthlink.net>
To: <hbr@mailman.qth.net>
Sent: Saturday, May 10, 2003 12:33 PM
Subject: Re: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6


> Mike Feher wrote:
> > Hate to be the "Devil's Advocate" here, And, posssibly you answered this
> > in a previous post. In either case, could you please remind of the
> > bandwidth that you are using to measure your noise floor?
>
> A lot of the reason for posting all that stuff is to get other thoughts
> and viewpoints.   If I knew what I was doing, I'd have finished the
> project six months ago.    Since this is in large measure a learning
> experience, please advocate!
>
> I measure the NF in the time-honored ham way -- with an AC
> voltmeter on the audio output; actually, across the primary of the
> output transformer.   I set the audio gain for a convenient reading on
> noise alone -- say 1 volt -- then apply the signal and adjust it for
triple
> the reading -- 3 volts in this case.   That would be roughly a 10 db
> ratio of (signal+noise)/noise.
>
> So the measurement bandwidth is set mainly by the audio bandwidth
> -- probably 5 kcs or so -- and the bandwidth of the filter in use,
> usually 2.4kcs.
>
> Such a casual approach can cause a few db error when comparing to
> measurements made on other sets and would show the HBR2K
> unfavorably if the other set measurement was made with a narrower
> bandwidth;  the effect would be 3 db/doubling, right?  Measuring at
> 4kcs would make the NF 6 db higher (worse) than measuring at 1
> kcs bandwidth.
>
> Of course my noise isn't uniformly distributed over the 4kcs -- there's
> more in the 2.4kcs corresponding to voice intelligence because most
> noise (now) actually comes from the mixers and must get through
> the filter. Only the 3180kcs IF noise (generated after that filter) is
> broadband enough to cover the audio section bandpass in a uniform
> fashion.
>
> (In very high quality receivers it is common to include a second
> selective filter at the end of the IF chain right ahead of the detector to
> take out the out-of-bandwidth IF generated noise but the added
> complication didn't seem worthwhile for this project.)
>
> I think the method is good enough for measuring my progress.   And
> the absolute answer it gives squares with my subjective impression --
> this receiver is 'getting there' but it is still too noisy.   I expect
that
> when a really good set is adjusted to comfortably receive signals on
> even a fairly quiet band (say, 20 when things are good -- does
> anyone remember the last time that happened?) if you then
> disconnect the antenna, the set goes essentially silent -- you might
> not know it was on.   HBR2K at its current state gets considerably
> quieter, but no one would yet call it 'silent.'
>
> Walt Hutchens
> 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 hbr@mailman.qth.net  Tue May 13 13:34:34 2003
From: hbr@mailman.qth.net (Diane Swynar)
Date: Tue, 13 May 2003 08:34:34 -0400 (EDT)
Subject: [HBR] =?iso-8859-1?Q?Re:_[HBR]_Front_Panel_Lettering=3F?=
In-Reply-To: <Pine.WNT.4.53.0305110714380.-151765@laptop>
References: <Pine.WNT.4.53.0305110714380.-151765@laptop>
Message-ID: <24150.198.208.6.35.1052829274.squirrel@webmail.durham.net>

Helm,

I swear by a peel-and-stick vinyl lettering product which is made by a
company called GEOGRAPHICS, based in Blaine, Washington...

For a couple of bucks you get a nice 8-1/2" x 11" sheet of all the letters
& numbers, & punctuation marks, in a wide variety of sizes. I like the
small stuff, which is less than 1/4" tall per character for my front panel
lettering. It's easy to apply, permanent (until such time as YOU wish to
remove it, that is, which is very easily done), and it looks great,
too...has the old DYMO lettering machine beat by a mile!

The better stationery/office su[pply shops sell it...comes in many
different colours & fonts, too.

~73!~ Eddy VE3CUI - VE3XZ




Yes, hobby shops which cater to RR and mdel airplane buffs carry
> several types a "decal" paper.  Works best with H-P and Epson printer
> types and inks.  Canon bubble printers don,t work.
>
> Regards,
> Helm.  WB2ADT  [K2, 2698]
>
>
> On Sun, 11 May 2003, Niel Wiegand wrote:
>
>> I recently acquired a restoration project (see:
>> http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).
>>
>> I'm going to have to redo the front panel. Any suggestions for the
>> lettering? Is there any material available that I can run through my
>> computer printer to make my own labels?
>>
>> 73,
>> Niel - W0VLZ
>> http://www.io.com/~nielw/wa5vlz.htm
>>
>> ************************************
>> 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 hbr@mailman.qth.net  Tue May 13 18:47:26 2003
From: hbr@mailman.qth.net (Mobile Engineering)
Date: Tue, 13 May 2003 12:47:26 -0500
Subject: [HBR] Re: [HBR] Front Panel Lettering?
In-Reply-To: <24150.198.208.6.35.1052829274.squirrel@webmail.durham.net>
References: <Pine.WNT.4.53.0305110714380.-151765@laptop>
 <Pine.WNT.4.53.0305110714380.-151765@laptop>
Message-ID: <5.2.1.1.2.20030513124358.00b16520@pop.mnic.net>

Eddy,

Did a cursory Web-search for GEOGRAPHICS and may have gone off in a wrong 
direction. Do you have any more specific info. on the particular product(s) 
you're describing...a part number and perhaps phone number or e-mail 
address for inquiring/ordering? Or do you know of an office-supply or other 
chain store which carries their product(s)?

Are their letters available in WHITE?

Thanks and 73's,

K0YQX

At 08:34 AM 5/13/2003 -0400, Diane Swynar wrote:
>Helm,
>
>I swear by a peel-and-stick vinyl lettering product which is made by a
>company called GEOGRAPHICS, based in Blaine, Washington...
>
>For a couple of bucks you get a nice 8-1/2" x 11" sheet of all the letters
>& numbers, & punctuation marks, in a wide variety of sizes. I like the
>small stuff, which is less than 1/4" tall per character for my front panel
>lettering. It's easy to apply, permanent (until such time as YOU wish to
>remove it, that is, which is very easily done), and it looks great,
>too...has the old DYMO lettering machine beat by a mile!
>
>The better stationery/office su[pply shops sell it...comes in many
>different colours & fonts, too.
>
>~73!~ Eddy VE3CUI - VE3XZ
>
>
>
>
>Yes, hobby shops which cater to RR and mdel airplane buffs carry
> > several types a "decal" paper.  Works best with H-P and Epson printer
> > types and inks.  Canon bubble printers don,t work.
> >
> > Regards,
> > Helm.  WB2ADT  [K2, 2698]
> >
> >
> > On Sun, 11 May 2003, Niel Wiegand wrote:
> >
> >> I recently acquired a restoration project (see:
> >> http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).
> >>
> >> I'm going to have to redo the front panel. Any suggestions for the
> >> lettering? Is there any material available that I can run through my
> >> computer printer to make my own labels?
> >>
> >> 73,
> >> Niel - W0VLZ
> >> http://www.io.com/~nielw/wa5vlz.htm
> >>
> >> ************************************
> >> 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 hbr@mailman.qth.net  Tue May 13 19:36:36 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 13 May 2003 14:36:36 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
In-Reply-To: <005f01c318bf$308a8370$0500a8c0@eoz>
Message-ID: <3EC102F4.10467.102A015@localhost>

Mike Feher wrote:
> This implies that your receiver's NF (noise figure) is 31 dB. Does
> that make sense? I would be surprised if it was over 15 dB. So, to
> me, right now things just do not add up. 

In other words, on fundamental theory it ought to be a heck of a lot 
quieter (more sensitive) than it is.   I agree with that, and that's why 
I'm still working on it!

Let's say a kid gets some bicycle wheels, a small block Chevy 
engine, the transmission from a riding lawnmower, a couple of V-
belts, um..., a 4'x8' sheet of plywood and a few 2x4's.   He has 
ridden in some cars and once made a soapbox racer so he decides 
to build a real car.   An engineer friend calculates that with the gear 
ratio he has, an engine of that displacement (etc.) the top speed 
ought to be 72 mph but the kid can only get 'er up to 30.   

The engineer's theory fails to take into account Designer Error.   
There's simply a lot more to stitching together a complete car (or 
receiver) than the fundamentals tell you.   In this case the 
fundamentals apply only to a receiver in which a reasonable input 
stage dominates the noise.   Well, of course that's how it *ought* to 
be.   But I am not there yet, and going by the direct route -- simply 
cranking up the gain of the RF stage -- would (at the current state of 
things) compromise the dynamic range.

One disadvantage I have is that when a design like this is done 
professionally the component parts are fairly well characterized by 
the manufacturers.   Custom parts are designed to specific targets.   
For example, the impedence of an IFT and the gain of a stage using 
a certain tube with that IFT would have been known before the stage 
was wired in a prototype.   Ditto the drive level for a certain crystal 
and the output a particular oscillator might produce with that crystal.  
Of course the optimum drive for a mixer would be known be before 
the prototype set was built.   And so on.

I'm working with ideas and bits of circuits from other designs that 
were incompletely tested (or at least, incompletely reported) and 
parts of somewhat unknown properties.   (1415 kcs IFTs retuned to 
3180 kcs, for example, for reasons of availablity and ease of 
modification.)   Some of the preliminary testing that I perhaps should 
do, I don't have the right instruments for.  Some I'm just too impatient 
to do -- I don't know what I *really* need until I see the problems and I 
fear spending a week studying something that turns out to be 
unimportant in the larger picture.   Probably this reluctance to do 
side-studies has hurt me, overall, but of course it's harder to see that 
one step at a time.

And then there are the 'just plain problems.'    When I began this 
note yesterday I was optimizing the 2nd mixer.  I had tried a couple 
of different circuits, minor variations on one of them, and was down to 
tweaking component values.   The trend was to better performance 
(IFDR) at higher mixer plate currents so (since I've got more overall 
gain than I need) I decided to raise the cathode resistor of the 2nd IF 
stage and save some ma there.    Huh?   All of a sudden the noise 
floor and IFDR took about a 2 db hit.   There's no logical reason they 
should be the least affected by the 2nd IF -- it shouldn't be 
contributing any noise, and indeed when everything up to there is 
disabled, the receiver is completely dead, even at full volume.   AGC 
is disabled for these tests so that couldn't be it.   It had to be a 
subtle feedback effect, but bedtime intervened.

In the early AM, sudden wakefulness.   There were a couple of 
obvious feedback paths from that last IF to early stages and I started 
by listening to the noise audio output with stages ahead of the 2nd 
mixer disabled.    Sure enough, there was a nearly inaudible signal 
that must have been coming in at around 3080.5 kcs -- so faint you'd 
never hear it with any other signal, let alone with an antenna 
connected.   I started poking around with bypasses and it was on the 
filament line, probably coming in through the power line despite a pi 
filter on the line input connector, the usual .01/2kv bypasses after the 
fuses and 0.1 bypasses at the main filament distribution point.  

If the filaments can propagate an external stray signal, they can do 
the same with an internal one -- there's a feedback path! 

I had wired all the filaments with 0.01 bypasses.  But the reactance 
of those at 3080 kcs is about 5 ohms -- not exactly a dead short, 
when filament levels of resistance (about 20 ohms per tube at 
operating temp) and tens or more of mmf filament to cathode 
capacitance are considered.   I got rid of the stray signal with 0.47 
bypasses where the filaments enter the front end compartment under 
the chassis.   And sure enough the noise level dropped a couple of 
db and the NF and IFDR are now the same with 150 ohms for a 2nd 
IF cathode resistor as with 68 ohms.   Most likely the path was from 
the cathode of the 2nd IF to the (unbypassed) cathode of the 2nd 
mixer, via the filament circuit.  The difference in feedback voltage 
when changing the cathode resistor was small, but there's a heck of 
a lot of gain (three very hot tubes) between those two cathodes and a 
2 db change in the noise floor caused by regeneration isn't much.   

In the future I'll be rewiring the filaments again and when I do, the 
bypasses will go from 0.01 to 0.1 from the 1st mixer on.    

I think you learn this stuff only by practical experience of which I 
didn't have enough for this job. Theory certainly does inform, but it 
doesn't let me avoid all such several-hour pitfalls.  I have assorted 
handbooks, but the approach is either -- "Build it like this" with a 
circuit diagram and where to get the parts (in 1965), or "Here's the 
theory of a receiver" with the parts being square blocks of specified 
gain and noise figure.   I really need a lab manual -- from about 1960 
or so.   As I write the 'notes' for the receiver -- 40 pages and counting 
-- I am including all the pitfalls I hit, so hopefully they only have to be 
hit once.

The grand plan has been to build the receiver from the power supply 
and audio, thence one stage at a time to the antenna, get it 
'basically working', then to repeat the journey from audio back to 
antenna making things as near 'really right' as I can.  I'm well along 
with the second pass; satisfied with everything from the filter driver on 
and probably close on the second mixer.  I need to finish up the 
optimization there, before moving back to the 1st mixer.   

A long story which I hope makes clear why a noise figure around 30 
db does not seem impossible right now, considering problems that 
may be lurking in the still only 'basically working' RF and 1st mixer 
stages.   I know for a fact that compared to really good receivers, this 
one is too noisy.  I strongly suspect the that 1st mixer has lower 
gain than it should because of insufficient injection.  The RF stage ... 
well, I'm pretty sure it's bad, although I can't tell you the details yet. 

I began with the belief that the set ought to be able to outperform an 
R-390 (IFDR around 80 db) because I've got better tube types and 
coils than were available in the 50's. I've seen nothing to change that 
view.  But it's still pretty far from there.

As always, thanks for the comments, Mike.   

Walt Hutchens
KJ4KV



From hbr@mailman.qth.net  Tue May 13 20:02:06 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 13 May 2003 15:02:06 -0400
Subject: [HBR] Front Panel Lettering?
In-Reply-To: <5.2.1.1.2.20030513124358.00b16520@pop.mnic.net>
References: <24150.198.208.6.35.1052829274.squirrel@webmail.durham.net>
Message-ID: <3EC108EE.28942.119F8E4@localhost>

Of course if you're going with somewhat standard wording on your 
panel -- as would usually be the case for an HBR -- then 'dry transfer' 
lettering is a good bet.   These are paint letters, available in standard 
titles ('GAIN CONTROL', 'TUNING' ...) for various trades and 
technologies, held on the back of a plastic sheet with a soluable 
wax.   

You paint your panel, put the title in the right place, and rub the face 
of the sheet with a ball point pen to transfer the letters.   When all 
the titles are done you should spray the panel with a clear fixative. 
The lettering manufacturers recommend their own because solvents 
in Krylon and similar products will enter the letters and cause them 
to wrinkle -- although if you are careful, you can get away with it.

Easy to use, look excellent, durable if properly coated.   A web 
search should turn up suppliers.   Datak is one brand, I also have a 
Mecanorama sheet or two.   Datak's #9581 (black) and #9591 (white) 
are 1/8" letter 'titles for electronic equipment.'   I believe they used to 
offer a separate product for amateur radio but that seems to be long 
gone.    Price in the $10-15 ballpark for 2200 titles (mostly stuff you'll 
never use) with alphabets and numerals for special cases.   

If you have patience and a steady hand the result looks as good as 
silk screen printing.   

IMO, computer printed decals only get the nod if you need lots of non-
standard text, a custom design, or non-standard colors.   And you do 
have to cope with limitations previously discussed.

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Tue May 13 20:13:11 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 13 May 2003 15:13:11 -0400
Subject: [HBR] Front Panel Lettering?
In-Reply-To: <3EC108EE.28942.119F8E4@localhost>
References: <5.2.1.1.2.20030513124358.00b16520@pop.mnic.net>
Message-ID: <3EC10B87.32222.1241FEB@localhost>

More dry transfer products, all from the KJ4KV Archives and available 
in electronic, amateur radio, and similarly appropriate sets.

MarKit, MarKit Jr.
Letraset
Datamark

Walt Hutchens
KJ4KV

From hbr@mailman.qth.net  Tue May 13 20:52:05 2003
From: hbr@mailman.qth.net (Eugene Rippen)
Date: Tue, 13 May 2003 12:52:05 -0700
Subject: [HBR] Front Panel Lettering, REVISITED
References: <5.2.1.1.2.20030513124358.00b16520@pop.mnic.net> <3EC10B87.32222.1241FEB@localhost>
Message-ID: <006401c31989$24bd3720$0100a8c0@tower>

I bet you all thought everything had been said about this subject.

Not necessarily so!

I have a HRO-50 cabinet that had been repainted.
The lettering is engraved into the front.
YEP!  The engravings got way too much paint.
Any suggestions as to cleaning out the engravings, and
getting the white paint into them?
That is, less than an all day job?
Or is it just tough for me, and I should get a small sharp
object, the magnifying goggles, and get to work and
quit whining?

Gene (Procrastinating)) Rippen


From hbr@mailman.qth.net  Tue May 13 21:19:07 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Tue, 13 May 2003 16:19:07 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
References: <3EC102F4.10467.102A015@localhost>
Message-ID: <001701c3198c$e89e2520$0500a8c0@eoz>

Walt -

I have no idea of engines, so will not comment on them. I also feel you need
to do this your way, and while you say you appreciate my comments, you are
obviously determined to get to the solution on your own, and, more than
likely I am interfering more than contributing to that end. So, please keep
us informed of your progress, and I promise I will refrain from further
comments. 73 - Mike


Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193



----- Original Message -----
From: <waltah@earthlink.net>
To: <hbr@mailman.qth.net>
Sent: Tuesday, May 13, 2003 2:36 PM
Subject: Re: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6


> Mike Feher wrote:
> > This implies that your receiver's NF (noise figure) is 31 dB. Does
> > that make sense? I would be surprised if it was over 15 dB. So, to
> > me, right now things just do not add up.
>
> In other words, on fundamental theory it ought to be a heck of a lot
> quieter (more sensitive) than it is.   I agree with that, and that's why
> I'm still working on it!
>
> Let's say a kid gets some bicycle wheels, a small block Chevy
> engine, the transmission from a riding lawnmower, a couple of V-
> belts, um..., a 4'x8' sheet of plywood and a few 2x4's.   He has
> ridden in some cars and once made a soapbox racer so he decides
> to build a real car.   An engineer friend calculates that with the gear
> ratio he has, an engine of that displacement (etc.) the top speed
> ought to be 72 mph but the kid can only get 'er up to 30.
>
> The engineer's theory fails to take into account Designer Error.
> There's simply a lot more to stitching together a complete car (or
> receiver) than the fundamentals tell you.   In this case the
> fundamentals apply only to a receiver in which a reasonable input
> stage dominates the noise.   Well, of course that's how it *ought* to
> be.   But I am not there yet, and going by the direct route -- simply
> cranking up the gain of the RF stage -- would (at the current state of
> things) compromise the dynamic range.
>
> One disadvantage I have is that when a design like this is done
> professionally the component parts are fairly well characterized by
> the manufacturers.   Custom parts are designed to specific targets.
> For example, the impedence of an IFT and the gain of a stage using
> a certain tube with that IFT would have been known before the stage
> was wired in a prototype.   Ditto the drive level for a certain crystal
> and the output a particular oscillator might produce with that crystal.
> Of course the optimum drive for a mixer would be known be before
> the prototype set was built.   And so on.
>
> I'm working with ideas and bits of circuits from other designs that
> were incompletely tested (or at least, incompletely reported) and
> parts of somewhat unknown properties.   (1415 kcs IFTs retuned to
> 3180 kcs, for example, for reasons of availablity and ease of
> modification.)   Some of the preliminary testing that I perhaps should
> do, I don't have the right instruments for.  Some I'm just too impatient
> to do -- I don't know what I *really* need until I see the problems and I
> fear spending a week studying something that turns out to be
> unimportant in the larger picture.   Probably this reluctance to do
> side-studies has hurt me, overall, but of course it's harder to see that
> one step at a time.
>
> And then there are the 'just plain problems.'    When I began this
> note yesterday I was optimizing the 2nd mixer.  I had tried a couple
> of different circuits, minor variations on one of them, and was down to
> tweaking component values.   The trend was to better performance
> (IFDR) at higher mixer plate currents so (since I've got more overall
> gain than I need) I decided to raise the cathode resistor of the 2nd IF
> stage and save some ma there.    Huh?   All of a sudden the noise
> floor and IFDR took about a 2 db hit.   There's no logical reason they
> should be the least affected by the 2nd IF -- it shouldn't be
> contributing any noise, and indeed when everything up to there is
> disabled, the receiver is completely dead, even at full volume.   AGC
> is disabled for these tests so that couldn't be it.   It had to be a
> subtle feedback effect, but bedtime intervened.
>
> In the early AM, sudden wakefulness.   There were a couple of
> obvious feedback paths from that last IF to early stages and I started
> by listening to the noise audio output with stages ahead of the 2nd
> mixer disabled.    Sure enough, there was a nearly inaudible signal
> that must have been coming in at around 3080.5 kcs -- so faint you'd
> never hear it with any other signal, let alone with an antenna
> connected.   I started poking around with bypasses and it was on the
> filament line, probably coming in through the power line despite a pi
> filter on the line input connector, the usual .01/2kv bypasses after the
> fuses and 0.1 bypasses at the main filament distribution point.
>
> If the filaments can propagate an external stray signal, they can do
> the same with an internal one -- there's a feedback path!
>
> I had wired all the filaments with 0.01 bypasses.  But the reactance
> of those at 3080 kcs is about 5 ohms -- not exactly a dead short,
> when filament levels of resistance (about 20 ohms per tube at
> operating temp) and tens or more of mmf filament to cathode
> capacitance are considered.   I got rid of the stray signal with 0.47
> bypasses where the filaments enter the front end compartment under
> the chassis.   And sure enough the noise level dropped a couple of
> db and the NF and IFDR are now the same with 150 ohms for a 2nd
> IF cathode resistor as with 68 ohms.   Most likely the path was from
> the cathode of the 2nd IF to the (unbypassed) cathode of the 2nd
> mixer, via the filament circuit.  The difference in feedback voltage
> when changing the cathode resistor was small, but there's a heck of
> a lot of gain (three very hot tubes) between those two cathodes and a
> 2 db change in the noise floor caused by regeneration isn't much.
>
> In the future I'll be rewiring the filaments again and when I do, the
> bypasses will go from 0.01 to 0.1 from the 1st mixer on.
>
> I think you learn this stuff only by practical experience of which I
> didn't have enough for this job. Theory certainly does inform, but it
> doesn't let me avoid all such several-hour pitfalls.  I have assorted
> handbooks, but the approach is either -- "Build it like this" with a
> circuit diagram and where to get the parts (in 1965), or "Here's the
> theory of a receiver" with the parts being square blocks of specified
> gain and noise figure.   I really need a lab manual -- from about 1960
> or so.   As I write the 'notes' for the receiver -- 40 pages and counting
> -- I am including all the pitfalls I hit, so hopefully they only have to
be
> hit once.
>
> The grand plan has been to build the receiver from the power supply
> and audio, thence one stage at a time to the antenna, get it
> 'basically working', then to repeat the journey from audio back to
> antenna making things as near 'really right' as I can.  I'm well along
> with the second pass; satisfied with everything from the filter driver on
> and probably close on the second mixer.  I need to finish up the
> optimization there, before moving back to the 1st mixer.
>
> A long story which I hope makes clear why a noise figure around 30
> db does not seem impossible right now, considering problems that
> may be lurking in the still only 'basically working' RF and 1st mixer
> stages.   I know for a fact that compared to really good receivers, this
> one is too noisy.  I strongly suspect the that 1st mixer has lower
> gain than it should because of insufficient injection.  The RF stage ...
> well, I'm pretty sure it's bad, although I can't tell you the details yet.
>
> I began with the belief that the set ought to be able to outperform an
> R-390 (IFDR around 80 db) because I've got better tube types and
> coils than were available in the 50's. I've seen nothing to change that
> view.  But it's still pretty far from there.
>
> As always, thanks for the comments, Mike.
>
> Walt Hutchens
> 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 hbr@mailman.qth.net  Wed May 14 01:25:41 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 13 May 2003 20:25:41 EDT
Subject: [HBR] Re: [HBR] Front Panel Lettering?
Message-ID: <177.1a7d61cc.2bf2e705@aol.com>

Some ideas I've used that haven't been mentioned yet.....

1) "Sandwich" front panel. Use a thin piece of clear Lexan, Plexiglas or 
Perspex the same size as the front panel. (Yes, twice as much drilling, but 
you can use the panel as a template). Between the Lex/Plex/spex and the front 
panle you "sandwich" a piece of Mylar tracing film on which the various 
labelings have been printed. Helps to have access to a big printer and a CAD 
package! Lotta work but looks sharp and the lettering will never wear off.

2) Do nothing. Most of my homebrew projects have no labels on the controls 
because I know what they do anyway, from building the thing. Really shakes up 
visitors to the shack, too. At least one commercially-made rx (RME-69) did 
this, on the theory that if you didn't have the sense to read the manual and 
find out what knob did what you shouldn't be using the rx in the first 
place....

73 de Jim, N2EY


From hbr@mailman.qth.net  Wed May 14 02:30:37 2003
From: hbr@mailman.qth.net (john)
Date: Tue, 13 May 2003 21:30:37 -0400
Subject: [HBR] Front Panel Lettering?
In-Reply-To: <3EC108EE.28942.119F8E4@localhost>
References: <5.2.1.1.2.20030513124358.00b16520@pop.mnic.net>
 <24150.198.208.6.35.1052829274.squirrel@webmail.durham.net>
Message-ID: <3.0.3.32.20030513213037.0287f190@pop-server.nc.rr.com>

Ocean state electronics (www.oselectronics.com) still has "ham radio"
dry transfers. Just got their new catalog
John K5MO


At 03:02 PM 5/13/03 -0400, waltah@earthlink.net wrote:
>Of course if you're going with somewhat standard wording on your 
>panel -- as would usually be the case for an HBR -- then 'dry transfer' 
>lettering is a good bet.   These are paint letters, available in standard 
>titles ('GAIN CONTROL', 'TUNING' ...) for various trades and 
>technologies, held on the back of a plastic sheet with a soluable 
>wax.   
>
>You paint your panel, put the title in the right place, and rub the face 
>of the sheet with a ball point pen to transfer the letters.   When all 
>the titles are done you should spray the panel with a clear fixative. 
>The lettering manufacturers recommend their own because solvents 
>in Krylon and similar products will enter the letters and cause them 
>to wrinkle -- although if you are careful, you can get away with it.
>
>Easy to use, look excellent, durable if properly coated.   A web 
>search should turn up suppliers.   Datak is one brand, I also have a 
>Mecanorama sheet or two.   Datak's #9581 (black) and #9591 (white) 
>are 1/8" letter 'titles for electronic equipment.'   I believe they used to 
>offer a separate product for amateur radio but that seems to be long 
>gone.    Price in the $10-15 ballpark for 2200 titles (mostly stuff you'll 
>never use) with alphabets and numerals for special cases.   
>
>If you have patience and a steady hand the result looks as good as 
>silk screen printing.   
>
>IMO, computer printed decals only get the nod if you need lots of non-
>standard text, a custom design, or non-standard colors.   And you do 
>have to cope with limitations previously discussed.
>
>Walt Hutchens
>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 hbr@mailman.qth.net  Mon May 12 13:57:27 2003
From: hbr@mailman.qth.net (David Newman W3HYM)
Date: Mon, 12 May 2003 08:57:27 -0400
Subject: [HBR] Front Panel Lettering?
References: <3EBE816B.8D88DD90@arrl.net> <3EBE8F31.B7B9FFC0@attbi.com>
Message-ID: <3EBF9A37.A4D733E7@ARRL.NET>

I have used decal sheets from Micromart, with  Color Laser printer.  Excellent results
for lettering.  Only problem, cannot  print white.  So I painted my panels for KW
amplifier BABY BLUE.  The BABY BLUE paint I obtained from an auto supply store.  First
prime then paint.  I then used black lettering on the light blue.  Also, I made some
fancier lettering with my callsign in red.  All looks good on the light blue.

I strongly recommend using laser decal paper, with laser printer.  Will work with laser
printer that prints black (normal laser printer).  You must get a preservative solution
to put on laser printer after you print the lettering.  Otherwise, lettering will come
off in water.  Micromart has a kit with all the necessary solutions, for about $16 or
$17.

Good luck!

David
W3HYM

fkamp wrote:

> Yes, indeed.  In the past I have made my own decals using the toner transfer method
> of making printed circuit boards.  You need a special paper and a laser printer to
> make it work.
>
> Normally you print out circuit traces onto the paper.  Then reactivate the toner
> with a clothes iron to transfer the toner to the copper. Then soak the whole thing
> in water to make the paper release from the toner.
>
> To make decals, you print out your artwork.  Then spray it with clear krylon or some
> other spray on laquer.  When the laquer dries, you float the paper in water and the
> decals release from the paper.  Works just like those decals I used to use on model
> airplanes.
>
> Do a search for dry toner transfer on the internet to see where you can get the
> paper.  I have also used high gloss ink jet paper.  It works too, but I have not
> tried it for making decals.  It is cheaper but if you only need a couple of sheets
> the price difference is not worth the hassle.
>
> Regards,
> Frank Kamp
>
> Niel Wiegand wrote:
>
> > I recently acquired a restoration project (see:
> > http://www.qsl.net/k5bcq/Morry/morryfront.jpg ).
> >
> > I'm going to have to redo the front panel. Any suggestions for the
> > lettering? Is there any material available that I can run through my
> > computer printer to make my own labels?
> >
> > 73,
> > Niel - W0VLZ
> > http://www.io.com/~nielw/wa5vlz.htm
> >
> > ************************************
> > 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 hbr@mailman.qth.net  Wed May 14 13:38:45 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Wed, 14 May 2003 08:38:45 -0400 (EDT)
Subject: [HBR] Front Panel Lettering?
In-Reply-To: <3.0.3.32.20030513213037.0287f190@pop-server.nc.rr.com>
Message-ID: <Pine.LNX.4.33.0305140837150.21933-100000@localhost.localdomain>

My two cents!

HBR does not need lettering.
Real radio op knows what the knobs do :-)

-Bob



From hbr@mailman.qth.net  Wed May 14 14:44:17 2003
From: hbr@mailman.qth.net (Mike Feher)
Date: Wed, 14 May 2003 09:44:17 -0400
Subject: [HBR] Front Panel Lettering?
References: <Pine.LNX.4.33.0305140837150.21933-100000@localhost.localdomain>
Message-ID: <001f01c31a1e$ec66d890$0500a8c0@eoz>

Believe it or not, those were the exact feelings of Shalkhauser, the founder
of RME. That is why all RME-69s that were manufactured never had any
labeling on any of the knobs, and, this was back in the '30s. 73 - Mike



Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193



----- Original Message -----
From: <bob@atl.org>
To: <hbr@mailman.qth.net>
Sent: Wednesday, May 14, 2003 8:38 AM
Subject: Re: [HBR] Front Panel Lettering?


> My two cents!
>
> HBR does not need lettering.
> Real radio op knows what the knobs do :-)
>
> -Bob
>
>
> ************************************
> 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 hbr@mailman.qth.net  Fri May 16 14:31:46 2003
From: hbr@mailman.qth.net (Eddy Swynar)
Date: Fri, 16 May 2003 09:31:46 -0400
Subject: [HBR] Lettering Front Panels...
Message-ID: <005f01c31bb1$74244040$d8d549c6@greg>

Hello All,

Somebody sent me a request this past week for additional information on the
lettering product I use to grace the front panels of my HB
creations---unfortunately, I DELETED the message in error...to whomever that
person is, SORRY!

I hope the group will indulge me a moment while I briefly respond to that
HB'er via this message...

The company's name (as indicated on the dunnage) is GEOGRAPHICS INC.,
Blaine, Washington 98230, USA. Yes, they DO make lettering in white...as
well as black, red, gold, & silver (more still, I'm sure, but this is what
I've seen on the shelves). Here in Canada, I buy mine from a stationery shop
called GRAND & TOY...although they are available at others, I'm sure.

If that person would like, I'd be more than pleased to try & dig up some
digital shots of the letters, as were employed in my HB linear
amplifier---just drop me a line c/o gswynar@durham.net

No, I am most assuredly NOT connected in anyway---financial, or
otherwise---with this company...however, I do NOT hesitate to plug a product
that I feel can be of tremendous benefit to HB artists, & which is
affordable & easy to use, to boot...

~73!~ Eddy VE3CUI - VE3XZ


From hbr@mailman.qth.net  Wed May 21 17:21:07 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Wed, 21 May 2003 12:21:07 -0400
Subject: [HBR] HBR2K -- Chapter 14 -- Large Signal Performance, Part 6
In-Reply-To: <134.1f94e418.2beed23a@aol.com>
Message-ID: <3ECB6F33.9380.67ECE9@localhost>

A couple weeks back, Jim, N2EY commented:
> I'm beginning to wonder if the performance of the HBR2K is actually much
> better than the test setup permits to be shown?

I looked at the design of the URM-25, found much good, and went on 
at length about it, but the comment stayed in my thoughts.   The 
other day, I thought of an issue I had not previously recognized, 
namely, second harmonic output from the generator.

Why does the second harmonic matter?   Well, receiver 3rd order 
IMD is measured by feeding it two signals 20 kcs apart.   The two 
signals are presumed 'pure'; the non-linearity of the receiver 
generates the second harmonic of each and mixes it with the other 
fundamental to give new signals 20 kcs higher than the higher input 
and lower than the lower one.   The ratio of these 20 kcs +/- signals 
to the input signals is a simple test of a receiver's ability to hear a 
'weak one' without being bothered by strong signals elsewhere on the 
band.

But what happens to the test if the signal generator isn't pure?  In 
particular, what if it supplies some 2nd harmonic energy?   Obviously 
the receiver performance 'looks' worse than it is.  I can't decide 
whether making measurements at various input levels would allow 
determining that the measurement was in error but I'm inclined to 
think not.   The distortion signals we're watching for (20 kcs above 
higher test signal and below lower) are actually generated in the 
receiver, whether the 2nd harmonic is generated there or comes from 
the sig gen.   Thus It seems to me that they would behave just like 
receiver distortion caused by overload from pure inputs and if so, Jim 
would be right ...

When measuring at the antenna, the receiver itself might provide 
useful attenuation of the sig gen's second harmonic.  But one tuned 
circuit isn't a lot -- maybe 20 db?  And most of the measurements I'm 
making now don't include a matched tuned circuit so there's no help 
at all.

I measured the 2nd harmonic output of one of the URM-25's.  Gee ... 
only 30-some db below the fundamental.   That seems to me to be  
really, really crummy if you want to measure dynamic ranges in the 
80-db area.   And the URM-25 design -- so good in other ways -- 
can't be helped in this department because everything is single 
ended and the design is optimized for wide frequency range rather 
than excellent linearity.   For example, the only tuned circuit is the 
oscillator tank itself.

So I spend the last week building a test oscillator.   Using the 
mechanicals and power supply from a GPM-15 LORAN test set I 
built up a push-pull Colpitts oscillator with a 6ES8 dual triode and 
followed it with a 6KE8 with the triode as a cathode follower and the 
pentode as a class 'A' linear amp.   The amp is cathode driven with 
negative feedback to the grid to set the gain and improve linearity.   

The oscillator covers 3-6 megacycles which includes all frequencies 
needed to test the HBR2K.   (Guess the source of the tuning cap 
and dial!)  The output stage is also tuned, to provide harmonic 
attenuation.   At present the 2nd harmonic is about 80 db below the 
fundamental, which should be good enough.

('About 80 db below ...' -- I have some leakage back through the line 
and some radiation so I cannot attenuate the fundamental more than 
about 80 db.   I know about some problems that could be causing 
the leakage, so in the next day or so I should have a better 
measurement.)

The project isn't quite done.  I have an amplifier output of about 5 
volts RMS but want 10 volts so a built-in 40 db attenuator can be 
used to get down to 100,000 uV at 50 ohms.   That 40 db of 
attenuation will give isolation from the other generator in addition to 
that from the hybrid combiner, helping to assure against non-linearity 
caused by the other signal; the URM-25 has only 20 db of internal 
isolation.

10 volts across 5000 ohms ought to be easy -- 20 mW, right?   But 
the stage has to operate well within the class 'A' range to minimize 
2nd harmonic generation.   So far it looks like the 6KE8 (basically a 
VHF TV oscillator/mixer tube) will only deliver about 5 volts unless 
the drive is raised enough to cause much more harmonic output.

I have some 6LQ8's on order; the pentode side of these is designed 
for video output service and has almost twice the gm and about half 
the plate resistance of the 6KE8.   I hope this tube will easily hit the 
10 volt mark If the 6KE8 won't make it.

Then I have to build a second generator.   And then the tests on the 
HBR2K can be repeated to see if the so-so IMFD showing is really 
the receiver or not.  Three weeks of preliminaries, 10 minutes of 
measurement.  Thanks Jim.   Really.  :)   

Walt Hutchens 
KJ4KV

From hbr@mailman.qth.net  Fri May 23 04:17:05 2003
From: hbr@mailman.qth.net (Helmut Usbeck)
Date: Thu, 22 May 2003 23:17:05 -0400 (Eastern Daylight Time)
Subject: [HBR] HBR-16
Message-ID: <Pine.WNT.4.53.0305222309410.-901677@laptop>

Greetings:

I need the HBR-16 template.  In what directory of HBR CD does it reside?
Been looking for it a while now and can't seem to find it.  Just need the
lay dimentions, I 'm not gong to be using the printout itself as a
drilling and hole punch guide.

Regards,
Helm.  WB2ADT  [Elecraft K2 #2698]


From hbr@mailman.qth.net  Fri May 23 18:34:40 2003
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Fri, 23 May 2003 12:34:40 -0500
Subject: Fw: [HBR] HBR-16
Message-ID: <20030523.123443.-204671.8.windy10605@juno.com>

Hi Helm,

I didn't put drill templates on the CD because they are oversize. I will 
be more than happy to send you a paper copy. Need your address.

73  Kees K5BCQ

--------- Forwarded message ----------
From: Helmut Usbeck <vze2gmp4@verizon.net>
To: hbr@mailman.qth.net
Date: Thu, 22 May 2003 23:17:05 -0400 (Eastern Daylight Time)
Subject: [HBR] HBR-16
Message-ID: <Pine.WNT.4.53.0305222309410.-901677@laptop>

Greetings:

I need the HBR-16 template.  In what directory of HBR CD does it reside?
Been looking for it a while now and can't seem to find it.  Just need the
lay dimentions, I 'm not gong to be using the printout itself as a
drilling and hole punch guide.

Regards,
Helm.  WB2ADT  [Elecraft K2 #2698]

************************************
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 hbr@mailman.qth.net  Sat May 31 09:40:30 2003
From: hbr@mailman.qth.net (Stan Wilson)
Date: Sat, 31 May 2003 03:40:30 -0500
Subject: [HBR] Next generation HBR-14 maybe
In-Reply-To: <002801c3017d$9e355160$6600a8c0@Dell8200>
Message-ID: <000001c32750$4b78c9e0$0101320a@CPU>

Even if you are not into solid state devices you have to appreciate the
craftsman shown in the CDG2000.  It got to be the next generation of
HBR.  The specifications exceed anything on the present market and there
is even a builders mail list on Yahoo where they exchange part sources
and solutions to building problems.  Enjoy the pictures their great,
compare some of the receiver specs with the proposed new ICOM or TenTEC

http://www.warc.org.uk/cdg2000/The%20CDG2000%20Transceiver.htm

de stan ak0b


