Originally Posted by dghutt
My voltmeter suggests a clue: the radio is only delivering 2.1 volts to the IC, although I'm getting 5.2v at the radio's "trainer" outlet, so I think something is backwards or mis-wired. I'll report here if further investigation doesn't get me anywhere.
plug in your circuit at the trainer port.
Don't switch on the TX, leave it powered off.
Setup your voltmeter to measure resistance. Use the lowest range (e.g.200 Ohm).
Measure the resistance
from pin2 at the port to pin 16 of the IC
from the solderpoint at the port, that corresponds to ground or -5Volt (black wire) to pin 15 of the IC
Both readings should be nearly 0 Ohm.
If one measure shows a higher value, that is probably your problem.