The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

Hi all!

I'm new here and was wondering if any one could give me a few pointers.
I got my hands on a couple of the old 23ch Cobra 29's and have a few questions: The final and driver-- The driver is a 2sc1226a and the final is a 2sc756. Is there anything I can/should replace the driver with? Is the 1969 going to be a direct electrical replacement to the 756? The 756 is a can-type (TO-5 I think?) so if the 1969 will work, it won't be a direct mechanical replacement, but that's no problem. Would I have to change any of the coils or caps to use a different final?
Are there any simple tweaks I can do (like spread a coil or adjust a coil or resistor) to get better modulation or swing?

Great site folks and thanks for your patience and any help you can give me.

I don't recommend messing with the driver transistor. Don't think there is much to be gained from doing that, unless it's broke.

The metal top-hat (TO-5) final transistor can be replaced with a 2SC1969.

Lining up the TO-220 final's leads with the right holes in the PC board is a pain. Especially if they are too short to reach.

Haven't done one of those in ten or fifteen years, so that kind of detail is fuzzy.

I do recollect one odd detail, though. That final transistor was made by Sony. There were two versions. One without the "A" suffix letter, and the one with. The "without" 2SC756 part was an audio amp. No RF power gain.

The "756A" is what the 29 used for a final. Meant as a RF power amp. The 1969 is more rugged under stress than the original part.

Pretty sure the alignment says to peak every transmitter adjustment on channel 12.

73