New answers tagged kenwood
3
I took it apart and found a transistor that had been blown apart, pictured below (the black one with its metal innards showing), likely from a scenario described by @rclocher3. This is the NPN transistor that supplies voltage to the blue PNP transistor and should be switching based on its base input but instead is supplying a constant 5V. No surprise there, ...
2
In the keyer, PNP transistor Q4 should be on when the keyer is supposed to be keyed. I assume that the transceiver's key jack goes to a CMOS high-impedance input and has a pull-up resistor, and that the key jack's sleeve terminal is tied to ground. If all that is correct, and if the keyer is working correctly, then the positive output of the terminal ...
2
FWIW: The Baofeng UV-5R HT supplies 3.3V through 100(*) ohms on the tip of the 3.5mm connector, not 5V as documented above. Also, the PTT is pulled up thru 10K to 3.3V, and the MIC+ connection line also has a more complex (constant current source?) pullup to 3.3V. [This is nice, as the PTT line can directly connect to a Raspberry Pi GPIO pin!]
There's a (...
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