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By "output line to the mic" do you mean where C1, C3 and R4 come together?The capacitors arrived today and I finished the project. However it is not working for me. When I key the mic it emits a high pitched wine to the receiver I have in the garage and also through the headset. I removed the mic and headset keyed the mic and it still emits the same wine.
I have checked it over three times and can not find any soldering problems or accidental groundings. I checked all of the connections for continuity to ground and they all appear to be good.
When I key the mic there is 6.15 +/- volts on mic hi and 3.0 volts on the output line to the mic.
I believe the battery switch is OK - when the mic is not keyed here is zero voltage on the emitter line from Q1 - when I key the mic there is 3.6+/- volts on the emitter line.
Yes.By "output line to the mic" do you mean where C1, C3 and R4 come together?
I connect my black tester lead to the ground plane of the circuit board and the other to the line to be tested.Are you measuring the voltages with respect to "MicLo" (which is the same as the radio ground)?
I am using the antenna attached to the hand held radio. There is a connector wire about 6" long to the circuit board. The connector wires to the headset are about 4' long.While you are transmitting, what are you using as an antenna, or are you using a dummy load?
Yes - it is the collector of Q1 with 3.6volts.You mean the wire labeled PP in the schematic. That would be the collector of Q1 (it is drawn upside down).
I'll see if I can find one at Radio Shack today.If it is RF getting into it, you could try adding a 1 nF (1000pF or 0.001uF or "102") capacitor in parallel with R5 to bypass any stray RF to ground from the base of Q2.
... When you say in parallel with R5 I assume you mean it will go beside R5 and connected to ground and the line out of Q2 the same as R5.