I gave up using the 5A rail that supplies the Microphone jumper and Microphone
socket for a preamp either internal or external - too much electrical noise, and
adverse effects on MCU operation etc.
Via Pin7 of P1 on the Front panel board I connected the 8A rail to the input of
a small 3 terminal 5V regulator (78L05) which is mounted on the Front panel
board. The regulator output has a 47uF and a 0.1uF capacitor to decouple it.
I disconnected the 5A supply feed to the Microphone jumper, and connected it
to the new +5V supply.
End result I can draw what current I need (within reason), there is NO noise,
and no possibility of upsetting the K2 firmware with loading or RF feedback.
73
Stewart G3RXQ
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