Transmits and receives no modulation out
I am not an expert but I think there can be little or no modulation of the carrier wave unless there is an audio input to the modulator. Like any audio amplifier a transmitter modulator (amplitude modulation) is quiescent without an input.
If the modulation amplifier and audio pre-amp are working and modulating the carrier wave and the antenna is ok then audio modulated radio frequency must be being transmitted.
It would be an extremely good quality CB that had a modulation meter. Mostly all they have is a meter giving an indication of the rf power being sent to the antenna and that rf (radio frequency) power would be the same whether modulated or unmodulated.
The modulation envelope, incidentally, is traditionally viewed or measured with an oscilloscope.
The indicated rf power could be verified using a field strength meter but the only practical way to discover if a standard CB is transmitting modulated rf is to listen to the transmission on a suitable receiver. If the squelch is turned down it will be obvious if the rf carrier wave is being received as the hiss would be silenced. If no audio is received it can be assumed none is being transmitted.
I suggest you try another microphone and lead and if that doesn't work it is clearly a job for a repair shop.
Oct 28, 2015 |