Fw: Re: [HBR] Another HBR Project -- Chapter 3

Sun, 31 Aug 2003 13:19:26 -0500

I think that's great Eddy.

As far as what's allowed on this site:

ANY discussion relative to HOMEBREW, TUBE (or hybrid) .....Receivers,
Transmitters, or Transceivers of a reasonable complexity level (superhet
receivers, etc). This may include: projects, stories, parts for sale,
parts wanted, technical discussions, new ideas, e-Bay alerts for homebrew
stuff, etc. It just started off as a site for HBR Receivers. 

73 Kees K5BCQ

--------- Forwarded message ----------
From: "Eddy Swynar" <[email protected]>
To: <[email protected]>, <[email protected]>
Date: Sun, 31 Aug 2003 09:08:36 -0400
Subject: Re: [HBR] Another HBR Project -- Chapter 3
Message-ID: <009301c36fc1$15caf660$ead549c6@greg>
References: <3F50BBA4.6743.157A971@localhost>

Hi Walt...

Very interested here in your on-going adventures with the HB rig---please
keep us advised, with my thanks in advance...

All this talk here of late has inspired ME to start laying out the parts
for
my own HB superhet. Perhaps it's a LITTLE off topic on this site because
it's NOT an HBR---still, the fact that it's homebrew is enough of an
accomplishhment in and of itself these days, I think, so here goes...

It's an 11-tube 1929-style superhet, as was inspired by TJ Lindsay's
piece
in the Antique Wireless Association's OLD TIMER'S BULLETIN of about a
year
ago...there ARE differences, however.

First-off, there'll be a 224A RF amp. The mixer & local oscillator will
be
224A's, followed by TWO stages of IF amplification c/o (you guessed it)
another pair of 224A's. The detector will be a non-regenerative 224A, and
the BFO will be a Hartley oscillator 224A. The first stage of AF
amplification will be 227---this will drive a p-p pair of 245's.

A 280 full-wave rectifier will provide some 250 VDC to the different
stages---I may have to cobble-up some multi-transformer concoction to
provide the some 17+amperes (at 2.5 volts!) filament
requirements...probably
a combo of 5-volt center tapped transformers, with "stand alone" 2.5
volts
from whatever transformer(s) I might find here. Shouldn't be a problem...

I plan on making BOTH IF stages regenerative, a la a technique espoused
for
ARC receivers in the first edition of UNDERSTANDING AMATEUR RADIO...and
yes,
I plan to "cheat" a little by using some vintage, NOS large Meissner IF
transformers that I have here in the junque box.

RF gain will be provided by virtue of a 500-ohm "attenuator" pot in the
antenna lead, ahead of the RF amplifier (there will be NO AGC). The front
main tuning dial came from a very neat, ancient old British(?) LF
receiver---it's finished in black wrinkle paint, & the dial arcs 180
degrees. Very smooth action, & it certainly has that "1929" look.

The goal here is to have this thing finished and operational by the end
of
November, in time for use in the AWA 1929 QSO Party...

I'll certainly be more than happy to keep the gang posted on developments
here, should the interest (if any!) from others merit the effort...

BTW Walt, I sure do miss your nuggets in ELECTRIC RADIO
magazine---whenever
I research my older issues on topics of interest, more often than not the
pieces have been penned by you! Thanks...

~73!~ Eddy VE3CUI - VE3XZ

----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Saturday, August 30, 2003 2:58 PM
Subject: [HBR] Another HBR Project -- Chapter 3

> Good progress this week.  Panel and chassis are done and power
> supply wiring is working.   The nearest thing to excitement was when
> the unused tap of one of the filament transformers shorted to the
> chassis and nearly cooked the thing.   The rest went smoothly
> including some tricky mechanical work for the command receiver
> plug-in coil unit -- glad that's behind me.
>
> The 6EW6 looks like a better local oscillator than the 6BH6 -- higher
> transconductance (14,000 vs. 4600) means less coupling needed
> between tube and tank circuit which means the tank has relatively
> better control over the frequency.   The price is greater heater power
> ... probably worth it since the layout allows keeping the heat pretty
> well away from the tank.
>
> W6TC certainly knew his practical theory:  using a pentode ECO not
> only gives you some isolation from the mixer but there's a lot of 2nd
> harmonic output and that's used in the HBR-series (as in similar
> commercial designs of the time) to get injection for the higher bands.
> It is a potential source of 'spurs' on 80-40 where the fundamental is
> used but with high-Q front end coils that should be a tolerable
> problem.
>
> Pictures -- captions follow each address:
>
> http://www.collie-rescuers.com/ebay/cistern3.jpg
>
> A first-rate workshop helps with these projects.
>
> http://www.collie-rescuers.com/ebay/hb1.jpg
>
> Chassis, panel, liberated 6-9.1 Mcs command receiver tuning cap.
>
> http://www.collie-rescuers.com/ebay/1stptst.jpg
> http://www.collie-rescuers.com/ebay/1stptsb.jpg
>
> Top and bottom views after 1st installation of parts -- +130 V, -160 V
> power supplies and filament transformers.   The negative voltage is
> needed for the AGC circuit.   Top view -- that's the output transformer
> between the two audio stages.   Other 'iron' L to R:  12VAC 1.2A
> xfmr, filter choke, 6.3-0-6.3 1.2A xfmr,  home made (primary x
> primary) 120VAC xfmr for plate supply.  Black objects in bottom view
> are filter caps.   The odd-shape socket (6U8 1st AF/phase splitter)
> is a Western Electric unit with three tie points mounted on each of
> two projections hanging off the sides -- very convenient when there
> are a bunch of parts to mount.   A flea market find ...
>
> Audio stages next.   I have been working about 5 hours a day so this
> might indeed be a 1 week project if one could go at it dawn to
> bedtime.
>
> 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

************************************
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