[HBR] Some Compactron modules

[Ian Wilson]

I couldn't resist tinkering. The RF module uses the 6BH11
(dual triode, pentode) as a 16MHz premixer VFO (this makes
sense, since you wouldn't want to use the pentode part of the
tube anywhere in the signal path). The LO part of the VFO is
one of my better efforts in terms of stability (by eyeball).

Two triodes of the 6AC10 are used in a Pullen mixer (the
plan was to have no RF gain ahead of this). The 9MHz output
is coupled through a tuned transformer to the xtal filter.

The schematic for the filter has 3 sections but I measure two
bumps. Also the bandwidth is about 3.4kHz while the schematic
claims 2.5kHz. So it looks as if I bypassed a section, or something.

I guess all this is telling me that I should rebuild the 9MHz IF
horror-amplifier instead of dumping it :)

73, ian K3IMW


On Wed, Jul 8, 2015 at 6:53 PM, Ian Wilson <ianmwilson73 at gmail.com> wrote:

> A few years back, I got part way through a receiver based
> on the 'KCS Compactron' (in two of the last issues of GE
> Ham News). Naturally I made some radical changes. My
> version used a 9MHz IF (instead of 455kHz), Pullen mixers,
> different tube lineup, etc. This had some promise but attempting
> to use the 6AR11 (twin high-gm semiremote pentode, TV IF amp)
> with inadequate shielding at 9MHz led to .. predictable results.
>
> Anyway. I don't seem to do anything with this except kick it
> around the floor. It was built on a number of single-sided PCB
> "modules" using ugly, er, ground-plane construction. There are
> three 5.5"x4.5" modules and one 9.5"x6" module. There is a
> nice premixer 16MHz VFO (high-quality air variable and ceramic former
> variable inductor, mixed with an 11MHz xtal osc). The modules are:
>
> RF: 6BH11 (dual triode + pentode); 6AC10 (triple triode);
>        VFO components and 9MHz homebrew filter
>
> IF: 6AR11 (dual semiremote pentode)
>
> BFO (9MHz)/Product detector: 6U10 (triple triode)
>
> Audio/AGC: 6T10 (beam power pentode + shpar cutoff pentode);
>            6U10 triple triode; small (8W) audio output transformer
>
> The Compactrons were all NIB and have a few hours of
> operation on them. The sockets are all high quality ceramic
> 12-pin Compactron.
>
> I actually have schematics for all the modules (they may have
> had work done on them but should save lots of detective work).
>
> I would like $15 for the set of modules plus shipping from
> 92620. Happy to trade for something as long as it's smaller
> and glowbug-oriented :)
>
> Please reply off-list. First come first served.
>
> 73, ian K3IMW
>
>