Paul, With an ohmmeter, everything will look shorted in the LPF section. If you have an antenna analyzer, you can remove the W1 jumper and terminate the LPF side with a 50 ohm resistor - connect the antenna analyzer to the antenna jack and scan through the filter passband - you want to do that for each band. If you see a large SWR, then check the LPF corresponding to that band.
A drop in signal at the receive output of the LPF could also be caused by a T/R switch problem. 73, Don W3FPR Paul Fletcher wrote: > > 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. > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
