[Heathkit] RP Electronics RPC-3.3U Speech Processor for SB-401

[jack m]

I recently demodified an SB-401 transmitter I am restoring including the removal of an RP Electronics model RPC-3.3U speech processor/compressor module (I think) mounted off the left side of the LMO.  The small SS module was installed in series with the microphone/phone patch inputs and the first audio stage by "lifting" one lead of the 22K resistors, and simply soldering the shielded cables between the board (input) and the combines lifted leads (output) of the resistors.  A rudimentary power supply was crafted underside using a dropping resistor and electrolytic capacitor off the B+ line.
 
The module has an "in/out" switch and a trim pot labeled "comp" as the only user adjustments.
 
I cannot locate any information on this module using the normal search modes and sites.
 
Do any list members recall this module?  I would liked to obtain a copy of any RP Electronics literature associated with it for future reference and possible installation on some other equipment.
 
Thanks
 
Jack  W3RU