You need a much smaller pot. Your TNC output is 250 times what the radio
needs, and the maximum output from your divider is 25 times what the
radio needs. Modern import pots don't do a good job of going to low
resistance. You'd do better with a 250 ohm pot and a 100K series
resistor. The TNC should also have an internal pot and jumper to allow
coarse adjustment of its output. Some I have seen have been modified to
give more output to drive Motorola VHF radios that need a volt or so.
Unless the microphone gain control is right at the microphone input,
your TNC output will overdrive the low level microphone stages without
the attenuator.
73, Jerry, K0CQ
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Entire content copyright Dr. Gerald N. Johnson. Reproduction by
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