From hbr@mailman.qth.net  Tue Mar 16 02:54:43 2004
From: hbr@mailman.qth.net (Bill Higgs)
Date: Mon, 15 Mar 2004 21:54:43 -0500
Subject: [HBR] Under construction HBR-??
Message-ID: <005801c40b02$08754600$6500a8c0@BILLDESKTOP>

Hello fellow solder junkies,

The HBR-?? ( who knows how many tubes this thing will end up with?) =
continues under construction both on paper and on metal. Having bowed to =
the sage advice of Walt and others, I have mounted the variable =
capacitor from my poor cannibalized BC-453 on the front panel. I was =
able to obtain a 454 cap from a fellow mad scientist (!), I compared the =
two side-by-side. Much to my surprise the plate shapes are identical, =
the caps only differing in the number of plates, and therefore the total =
capacity. With this in mind, I'm either going to go with a high c =
oscillator circuit, or put a series mica in line, and then live with =
whatever nonlinearity I encounter. After looking through one of the =
early "Single Sideband for the Radio Amateur" books, it seems that =
several of the fellas used the 454 cap for roughly a 5.2-6.2 Mc tuning =
range, and the pix showed a dial with reasonable linearity (no worse =
than about 2:1). I played around a bit with my 453 cap, a toroid, and an =
FET (shudder!), and was able to get about a 3:1 linearity (tightest =
100kc was about 1/3 the space of the widest 100kc) while tuning =
5050-5750. Output was a bit lower than expected, so the high C circuit =
might not work (either in tube or FET configuration). The final =
receiver, of course, will use a tube.

The mechanical work has gone smoothly. I found a pan-shaped aluminum =
piece (obtained surplus several years back; probably the front/rear part =
of an old Bud cabinet) which was just about the right size to cover the =
dial and the tuning knob. I drilled a roughly 2" hole for the knob, so =
it's recessed a bit, then made a plate of clear plexiglass with a =
clearance hole for the knob which serves to keep scratches off the front =
and also serves as the window to the readout dial. The whole assembly =
looks nice and serves to strengthen the mounting, keeping the chassis =
and the front panel somewhat more rigid. I'm tempted to bore a hole =
through the bottom of the capacitor frame and fasten to the chassis, =
giving even more rigidity. A few holes, a coat of dark green paint on =
the pan and flat black on the front and rear panels, and it's ready to =
label. I'll post a photo as soon as my daughter shows me how to work the =
digital camera . . .

A couple of questions to the group: First, has anyone tried to use a =
Vackar of Seiler oscillator with either the usual HBR mixer or with a =
beam deflection mixer? If so, your thoughts?? It looks as though I might =
be able to configure a bit more C in either of these circuits, thus =
improving possible dial linearity, and possibly keep the output stable =
over a somewhat broader (700kc) range.

Question two regards the gain controls on the RF, Mixer, and IF amps. =
I'm looking seriously at the hang AGC circuit, which appears to have =
provision for manual or concurrent gain control by feeding a negative =
voltage into the circuit at the recovery diode and/or the agc line (I'd =
isolate it through another diode, though . . .) The 5W wirewound =
resistors in the values W6TC specified are practically "unobtainium" =
nowadays, and most catalogs jump from 2W to 12W. Digi-Key advertises 5W =
CTS wirewounds at $2.50 each, but the values run 1K, 5K, 10K and 25K. =
Since the point of this pot is to adjust the cathode bias from zero to =
some positive voltage (thus biasing the control grid negative), I have =
also thought of developing a negative voltage from a doubler off the =
filament line, and using a higher value pot to control a negative =
voltage to the tubes via a diode (my thinking is that as the grid is a =
higher impedance point, less dissipation on the part of the pot. Other =
idea (not quite Kosher), is to run the cathodes off a power transistor =
(2N3055?) controlled by a smaller pot, since the cathodes are fully =
bypassed. This keeps the solid state out of the signal path, at least. =
But does put silicon inside the box, which sort of defeats where we're =
going, doesn't it?

Anybody have any ideas on this one? I have yet to cut too many holes in =
the chassis, so I am still open to suggestions at this point. By the =
way, I did go with an external power supply. Gives more room to mount =
stuff (see hang AGC above, audio filter, noise limiter, ??), and keeps =
the hum generator well away from hard-to-shield beam deflection tubes.

73 to all,


Bill Higgs, NT4C

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From hbr@mailman.qth.net  Tue Mar 16 05:06:23 2004
From: hbr@mailman.qth.net (LORNE BARBER)
Date: Mon, 15 Mar 2004 21:06:23 -0800
Subject: [HBR] hbr project
Message-ID: <000301c40b14$7121aba0$25897240@default.sunwave.net>

I found this Home brew receiver project on the auction site.
It is an impressive project with nice pictures.
This is for information only, I have absolutely no connection
with the listing. Thought some would enjoy seeing what others
have accomplished.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3085045706&c
ategory=4673

73
Lorne VE7BOX


From hbr@mailman.qth.net  Tue Mar 16 14:23:19 2004
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 16 Mar 2004 08:23:19 -0600
Subject: [HBR] hbr project
Message-ID: <20040316.084955.556.6.windy10605@juno.com>

Very interesting receiver, has had lots of hits so others are interested
too. Indications are that the builder was quite proud of it himself
because of all the specification documentation including on the unit.
This one has to have a real history associated with it. Hope someone in
the group ends up wit it and tells us how well it works.

Thanks for keeping an eye out, Lorne. I've been spending time
building/kitting the R/C MicroStar 2000 radio for a few folks around
here, if you are interested, Lorne. 

73 Kees K5BCQ

From hbr@mailman.qth.net  Tue Mar 16 15:15:13 2004
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 16 Mar 2004 10:15:13 -0500 (EST)
Subject: [HBR] HBR guys who do not read glowbugs might want to subscribe and look
 at archives
In-Reply-To: <005801c40b02$08754600$6500a8c0@BILLDESKTOP>
Message-ID: <Pine.LNX.4.33.0403161012220.20068-100000@localhost.localdomain>

There has been a lot of discussion on the glowbugs
mailing list recently re: the ultimate RX and some
of the discussion might apply to anyone building an
HBR.

In particular, there has been a lot of talk on mixers
including the 'Pullen' and mixers using sheet beam
tubes from TV's (as opposed to the expensive RCA
that was used in the Squires Sanders and some others)

Just a heads up...

-Bob
ah7i/w4 honolulu/atlanta



From hbr@mailman.qth.net  Tue Mar 16 17:12:27 2004
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 16 Mar 2004 12:12:27 EST
Subject: [HBR] Under construction HBR-??
Message-ID: <15a.301bc093.2d888f7b@aol.com>

In a message dated 3/15/04 9:56:11 PM US Eastern Standard Time, 
Bill@LizCurtisHiggs.com writes:

> 
> The HBR-?? ( who knows how many tubes this thing will end up with?) 
> continues under construction both on paper and on metal. Having bowed to the sage 
> advice of Walt and others, I have mounted the variable capacitor from my poor 
> cannibalized BC-453 on the front panel. I was able to obtain a 454 cap from a 
> fellow mad scientist (!), I compared the two side-by-side. Much to my surprise 
> the plate shapes are identical, the caps only differing in the number of 
> plates, and therefore the total capacity. With this in mind, I'm either going to 
> go with a high c oscillator circuit, or put a series mica in line, and then 
> live with whatever nonlinearity I encounter. After looking through one of the 
> early "Single Sideband for the Radio Amateur" books, it seems that several 
> of the fellas used the 454 cap for roughly a 5.2-6.2 Mc tuning range, and the 
> pix showed a dial with reasonable linearity (no worse than about 2:1). I 
> played around a bit with my 453 cap, a toroid, and an FET (shudder!), and was 
> able to get about a 3:1 linearity (tightest 100kc was about 1/3 the space of the 
> widest 100kc) while tuning 5050-5750. Output was a bit lower than expected, 
> so the high C circuit might not work (either in tube or FET configuration). 
> The final receiver, of course, will use a tube.
> 
> 

Bill,

The following is something I posted back in February.  I couldn't find an 
archives on the web for this list, so I had to type it again.

I got involved in designing a linear tuning capacitor VFO about 30 years ago 
while in college.  Here is what I came up with for the theoretical shape of 
the plates of a linear-with-frequency tuning capacitor:

R = SQR((-4*K)/(H*(K*A+F2)^3)+C^2)

Where:
R == Radius of plates as a function of rotation (inches)
A == Angle of rotation (radians) - the variable in the equation
K == Rate of frequency change with rotation - (Hz/rad)
F2 == Higher frequency (freq with plates unmeshed) (Hz)
C == Radius of cutout in stator to clear the shaft (inches)
H == Ck/(F1^2*C1)
    Where: Ck == Farads per square inch of capacitor used - this accounts for 
the plate spacing and number of plates
        F1 == Lower frequency (Hz)
        C1 == Capacitance at F1 (Farads)

The equations look much simpler when you put them in standard math notation.

Since this is only theoretical, fringing of the electric field is neglected, 
but this should have only a minor effect.

If you use a BASIC program or MATHCAD, etc., to plot the shape of the plates 
it is very enlightening.
The smaller the frequency range, the more nearly circular the plates need to 
be.  For a small range like a ham band the plates look almost like a circle 
with the shaft offset from the center.

Dan K9WEK

Please don't be offended with all of this.  This will give you the shape of 
the plates, the real problem is finding or modifying a capacitor to have this 
shape.  Once you see what it should look like though, it gives you a starting 
point.  You can also play games like changing the frequency ratio until the 
shape matches a capacitor you have.

If there is something you don't understand about the above info maybe I can 
help clear it up some.

Thanks,
Dan K9WEK


 


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From hbr@mailman.qth.net  Tue Mar 16 23:29:04 2004
From: hbr@mailman.qth.net (Darrell, WA5VGO)
Date: Tue, 16 Mar 2004 17:29:04 -0600
Subject: [HBR] Under construction HBR-??
In-Reply-To: <005801c40b02$08754600$6500a8c0@BILLDESKTOP>
Message-ID: <5.2.0.9.2.20040316172114.00b300f0@mail.earthlink.net>

I have been using quality (Allen Bradley) carbon pots in several HBR's in 
both the gain controls and the S meter circuit for years without a single 
failure. The need for wirewound pots seems to be overstated.

A hang AGC is the only way to go. The circuit I'm using is pretty much 
straight out of the ARRL Handbook and it's a vast improvement over the one 
used by Ted. I found that feeding it from the IF worked much better that 
from the audio.

Keep us posted.
Darrell, WA5VGO



At 09:54 PM 3/15/2004 -0500, Bill Higgs wrote:
>Hello fellow solder junkies,
>
>
>
>Question two regards the gain controls on the RF, Mixer, and IF amps. I'm 
>looking seriously at the hang AGC circuit, which appears to have provision 
>for manual or concurrent gain control by feeding a negative voltage into 
>the circuit at the recovery diode and/or the agc line (I'd isolate it 
>through another diode, though . . .) The 5W wirewound resistors in the 
>values W6TC specified are practically "unobtainium" nowadays, and most 
>catalogs jump from 2W to 12W. Digi-Key advertises 5W CTS wirewounds at 
>$2.50 each, but the values run 1K, 5K, 10K and 25K. Since the point of 
>this pot is to adjust the cathode bias from zero to some positive voltage 
>(thus biasing the control grid negative), I have also thought of 
>developing a negative voltage from a doubler off the filament line, and 
>using a higher value pot to control a negative voltage to the tubes via a 
>diode (my thinking is that as the grid is a higher impedance point, less 
>dissipation on the part of the pot. Other idea (not quite Kosher), is to 
>run the cathodes off a power transistor (2N3055?) controlled by a smaller 
>pot, since the cathodes are fully bypassed. This keeps the solid state out 
>of the signal path, at least. But does put silicon inside the box, which 
>sort of defeats where we're going, doesn't it?




From hbr@mailman.qth.net  Thu Mar 18 04:20:51 2004
From: hbr@mailman.qth.net (Ken Evans)
Date: Wed, 17 Mar 2004 23:20:51 -0500
Subject: [HBR] Eddystone Dials on E-bay
Message-ID: <00da01c40ca0$65cfe2c0$6401a8c0@pawpaw>

Anyone interested there are two Eddystone dials on e-bay.

Item numbers  3085556001 and 3085556103.  After seeing what the last one
went for, I am tempted to sell mine.

Ken
W4DU
Vice President - QRP ARCI
QRPARCI #696, GQRP#5918, FP#295, ARRL - Life



From hbr@mailman.qth.net  Tue Mar 30 18:29:57 2004
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 30 Mar 2004 12:29:57 -0600
Subject: [HBR] membership
Message-ID: <20040330.122957.1068.5.windy10605@juno.com>

I just added another 3 new members. We're now at 119. How are all those
projects going ?  Yes, one of my projects is to get some more HBR
pictures on-line. I have about 6 to put up. Radio Control has been taking
up much of my time lately ...it's a nice variety, old tube receivers and 
kitting PIC controllers for R/C, with a touch of Heathkit SB-104A, and
making a pass at restoring a SP-600 front panel.

73 Kees K5BCQ

From hbr@mailman.qth.net  Tue Mar 30 21:03:02 2004
From: hbr@mailman.qth.net (hbr@mailman.qth.net)
Date: Tue, 30 Mar 2004 16:03:02 -0500 (EST)
Subject: [HBR] membership
In-Reply-To: <20040330.122957.1068.5.windy10605@juno.com>
Message-ID: <Pine.LNX.4.33.0403301557390.19589-100000@localhost.localdomain>

My projects are going out the door.

Still don't have a house in Hawaii and no room
in the apartment.

That HBR in the big box is forsale if anyone is interested.
Also have a 500kc IF strip with 3 tuned circuits if anyone
is building with 500kc xtal filter.

Have a Johnson Navigator on the bench. Always wanted one.
This one came stuffed full of relays, choke burned up,
missing the VFO/xtal switch, power supply miswired using
solid state parts( and NO FILTER CAPS!), missing VFO enclosure,
and kind of nasty looking in general. But, it's a Navigator
and it was cheap! So far have PS and metering fixed. Gonna
dispense with xtal option as the switch will be impossible
to find. Should have it runnign by the end of the week.

-Bob





From hbr@mailman.qth.net  Tue Mar 30 22:15:46 2004
From: hbr@mailman.qth.net (john)
Date: Tue, 30 Mar 2004 17:15:46 -0500
Subject: [HBR] membership
In-Reply-To: <Pine.LNX.4.33.0403301557390.19589-100000@localhost.localdo
 main>
References: <20040330.122957.1068.5.windy10605@juno.com>
Message-ID: <3.0.3.32.20040330171546.027a4930@pop-server.nc.rr.com>

How much for the HBR Bob?
Thanks!
John


At 04:03 PM 3/30/04 -0500, you wrote:
>
>
>My projects are going out the door.
>
>Still don't have a house in Hawaii and no room
>in the apartment.
>
>That HBR in the big box is forsale if anyone is interested.
>Also have a 500kc IF strip with 3 tuned circuits if anyone
>is building with 500kc xtal filter.
>
>Have a Johnson Navigator on the bench. Always wanted one.
>This one came stuffed full of relays, choke burned up,
>missing the VFO/xtal switch, power supply miswired using
>solid state parts( and NO FILTER CAPS!), missing VFO enclosure,
>and kind of nasty looking in general. But, it's a Navigator
>and it was cheap! So far have PS and metering fixed. Gonna
>dispense with xtal option as the switch will be impossible
>to find. Should have it runnign by the end of the week.
>
>-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
>
>
>
>---
>
>Checked by AVG anti-virus system (http://www.grisoft.com).
>Version: 6.0.622 / Virus Database: 400 - Release Date: 3/13/04
>


---

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.622 / Virus Database: 400 - Release Date: 3/13/04


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