No modulation on SSB using internal mic

[dervari]

Just received an assembled kit and after adjusting the clock frequency am impressed by the RBN reports. However, I went to chase a couple of POTA activators using SSB and got nothing. I then tried listening in on another rig and am getting no modulated audio when using the internal microphone. The box shows T on the display, so the internal PTT button appears to be functioning normally.

I've verified that when noting is plugged into the mic/key jack that MK1 Pin 2 has continuity to Pin 16 on the MEGA and Pin 4 on the ISP header. Pin 1 is properly connected to GND. When a plug is inserted, MK1 Pin 1 loses continuity to the MEGA and ISP header.

This seems to indicate a bad mic element. Any second opinions?

Has anyone had to replace the mic and if so, do you have a BOM or part number I could reference?

Thanks!

[Ohwenzelph]

I don't know if the mic itself is the problem, Manuel has stated that too much heat for too long can unsolder the internal components of the mics, the data sheets seem to want you to place the body of the mic into a hole in a block of aluminum for a heat sink while soldering them. So probably better to not linger while soldering and I don't think you have to mount it flush to the board.
For a replacement I think this mic pretty closely matches the specs for the normally supplied mic
490-CMEJ-0627-42-P
At mouser. If you look it up at mouser the same one can be also obtained from digikey and other sources. I have tried one and it seems to work well.
Good luck & 73

p.s. also, it's possible to install them backwards, so check for that.

[dervari]

Thanks. Ordered a few from Mauser along with some Amphenol LMR400 connectors.

[DL2MAN]

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