[Milsurplus] TBW and 800 cycles

[Ray Fantini]

I have spent some time running a TBW whose center section was gutted when I got it. Building up the 60 cycle AC power supplies and getting them to fit in the center section was not that big of a deal except I kept the plate supply separate, but the original design relied on short time constant values of the filters to prevent keying chirps and a very annoying habit of the MO producing a annoying chirp that drifted down the band after you let up on the key. In the end in order to keep the same keying system in place had to use external bias voltage on the IA stage and do much experimentation on values of filter capacitors and bleeder resistors to get the radio to sound right. Unless you want to do lots of work would think your better off using the original 800 cycle power source being much of the design of the TBW was biased on that, way more than just using raw AC to provide the side tone for A2 operation. Would be curious to know if the same short time constant circuits and primary AC keying were used in the GP transmitters? Another interesting side note, the ARC-38 and 618S transceivers all used the 6 volt 400 cycle buses to provide CW side tone for the operator in the CW mode, what other transceivers did this too?
Ray Fantini KA3EKH