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 _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
