Re: radio will transmit CW but not voice



I should have also said that I am using an SDR as a receiver.  On the waveform when I key the microphone I see nothing.  Whilst, when I key the microphone with CW selected I can see the signal loud and clear.




From: <> On Behalf Of Evan Hand
Sent: Saturday, April 17, 2021 8:38 PM
Subject: Re: [BITX20] radio will transmit CW but not voice



The first thing to do is always verify that the measurement is correct.  In this case that both rigs are set up to receive the other rig.  Same frequency and sideband.

Assuming that is correct, and still no audio, then I would suspect the microphone.  What test equipment do you have to help in diagnosing the issue?  At this point an oscilloscope would be nice, however, an RFProbe with a DMM can help in tracking the signal from the mic to the product detector/modulator if you do not have an oscilloscope.
Here is how to build one if you do not have an RF probe or oscilloscope:

Another test is to connect an audio tone source (your PC with an audio tone program as an example) and then key the PTT ring.  I made an adapter that connects the tip of a 3.5mm plug with the tip of the plug to the computer, shield to shield, and a switch between the shield and the ring of the plug that goes to the rig mic input.  If you get rf out of this setup then the mic is most likely the issue.

Let us know what test equipment that you have so we can give you suggestions based on your equipment.

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