I recently picked up a TPL Tempo amplifier from a local SK estate sale. The amp is specified as a Class C (FM only) amp; 10 watts in, 110 out. The power amplifier consists of three B40-12 transistors in parallel, with a fourth apparently serving as a pre-amp. There are a number of old TPL amp manuals available online, but none for this particular model, so I don't have a schematic.
The seller told me the amp had been modified by the prior owner to bias the power transistors so that it now functions as a Class A amp with 70 watts out. I've opened the case and there appear to be some circuit mods, but I can't tell whether they do what they are purported to do.
I have found a one-page spec sheet for the B40-12 transistor, which characterizes it as designed for use in Class C amps for mobile FM operation.
So here's the question: is anyone on the list sufficiently familiar with the TPL Tempo to advise (a) whether it can indeed be modified to serve as a class A amp, and (b) what the mods would look like.
thanks, and 73
Lew N6LEW
Lew Phelps N6LEW
Pasadena, CA DM04wd
Elecraft K3-10
Yaesu FT-7800
[hidden email]
www.ntlew.us
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