Re: K2 signal tracing progress and questions arising

Posted by Paul Fletcher on Nov 11, 2009; 9:47pm
URL: http://elecraft.85.s1.nabble.com/K2-signal-tracing-progress-and-questions-arising-tp3982841p3989194.html

Don Wilhelm-4 wrote

Paul,

My only thought on the bandpass filter "weirdness" is that either the
bandpass filter is not properly terminated at the D6/D7 junction, or
that your 'scope probe is picking up something extraneous - change the
routing of the ground on the 'scope probe and see if there is any change.

OK fixed the voltage discrepancy by limiting the bandwidth on the scope (measurement issue). One problem appears to be in the chain up to the receive mixer. I'm losing about half of the signal but I'm not sure if it's the low pass filters or something after the LP filters pulling the signal down. Next steps are to check for ground shorts in the LPF bank. Another check I thought of doing is terminating the LPF (by opening W1) into a 50 ohm resistor and checking that out. If that's OK open W6 and do the same check (to check the T/R switch).

Any other suggestions?

Cheers,
Paul.