[Collins] 75A3 accessory?

[Jim Brannigan]

Adding a product detector to the A3 was a common mod.
There were a few commercial products around, but most were homebrew.
It should not be too hard to reverse engineer and draw a schematic.
Jim

> Dear Collins Guru's
> 
> The 75A3 I recently received came with a little mystery.
> 
> It was plugged into the NBFM adapter socket. However, when reading the
> manual I see that the xtal calibrator is a single 6BA6, and the NBFM
> adapter is TWO tubes, a 6AU6 and a 6AL5.
> 
> The adapter I have has a single 12AU6A on top of an IF can that
> presumably holds circuitry. When it is plugged in, it is in a diamond
> aspect with the back of the chassis, rather than parallel.
> 
> When examined, the socket has been rewired.
> 
> Might the beastie be a product detector?
> 
> If so was that a Collins mod, and is there a schematic around?
> 
> Many thanks & 73,
> 
> Guy.