Improvement / adjustment of the standard microphone of the Inrico TM-7

From various stations I was told that the modulation of my TM-7 was rather shrill.
On this I decided to replace the standard microphone (internal) with an electret microphone.
In order not to burden the TM-7 extra, I decided not to extract the required voltage from the device (via the microphone connector) but to use an external power supply for the electret microphone.
This requires:

1 – Three wire electret microphone (with separated + wire)

1 – Button cell battery

1 – Button cell holder

I have connected the new microphone according to the diagram below.

After a number of QSO’s tests, the adjustment proves to be a huge improvement on the standard situation. The modulation is said to be nice and full and not that sharp anymore.

by Marcel Goedemans