03-02-2009, 09:17 PM
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Join Date: Dec 2008
Location: Silicon Valley CA, Storm Lake IA
| | D104 Mic/Amp Transistors...Gone Bad?!?
So, I bought a D104 from eBay and wired it up for the standard Ranger/Magnum arrangement. Popped a new battery in it an plugged it in. Key it up and it is making noise and acts like the contacts on the leaf switch are dirty. Fine. So I get a thin, fine file and clean off the contacts a little bit. Presto; no more intermittent key-up. But now, there is another problem.
It appears that the mic can talk, but the modulation is way, way low - even when turned up all the way in the mic. And the radio mic gain is way up - too. I'm beginning to wonder if the transistors in this thing are gone - because there is no gain from the mic. Are the 2N2712 transistors known for failing - or is there another problem with this mic I haven't yet tracked down. Additionally, I also went over all of the solder joints on the amp board to make sure there weren't any bad joints. I'm wondering if I overlooked anything - or do these transistors in this mic have a history of going bad.
BASE: Kenwood TS-2000, GAP Titan DX, Diamond X50A, Sirio SY27-4, and IMAX 2000.
MOBILE: Galaxy DX99V w/RF Limited CR-577 mic, Sirio Z-180. Yaesu FT-8800R & Diamond NR-770.