Thank you guys
@Sooty25 I had the same thought and have tried it with un-modified connector, made no difference.
No I didn't select "externa mike" - didn't realise you had to. In all my previous radios you just plugged in external mike without having to set anything...
Will test and report.
Dynamic mike from LX is 200 Ohm, so that might be the reason it doesn't work so well?
I have since found these mikes:http://www.pilot-usa.com/headset-access ... pa-7x.html
I have been assured that they work fine with FTA-450/550, and I guess they should since they are meant for aviation headset.
The only thing that puzzles me is, that these "...microphone requires a DC voltage supply of 9-28 volts. This voltage is standard with modern aviation equipment..."
I have measured voltages on my Yaesu (without mic connected) and I get:
3.24 volt is on PPT line. When I ground it, the voltage on MIC line goes from 0 to 5.08 volt .
Yet it is supposed to get at least 9 volts for this amplified mike to work?
Bear in mind that I am mechanical engineer and not electronic
so I might be talking out of my rear orifice ...
@Paul_Sengupta indeed, and that is possibly my problem... instead of mike as used in typical aviation headset, I have tried using either electret or dynamic boom mike as used in gliders. I guess these are not amplified? and that is why?
I was OK previously with old Icoms and Delcoms, but Yaesu must be different?