On my K2 (#3014) I hear signals and noises while tuning across 160m with the antenna disconnected. The worst is a strong but unstable signal that moves from about 1850 kHz to about 1910 kHz during about 15 minutes after I switch on the radio. I accidentally traced the signal to U10C on the control board: the signal jumped when my finger got near the left end of resistor pack RP2. (U10C appears to be a buffer for the V BIAS-XFIL line.)
The signal is several kHz wide and resembles hash from a dimmer or switching power supply. I have verified the U10 circuit resistors and voltages as nominally correct. U10D, an identical circuit for the V BFO line has pretty clean dc at its output. Has anyone else seen this? Am I correct in concluding that I should replace U10? 73, David, NM5U ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
