> John, > For the time being (until you solve the current problem) the only voltages > at U6 that matter are pins 1, 2 and 3 - and those are correct. The other > pins will likely fall into line after you have this problem fixed and if not > there is another problem with the VCO.
> Right now, the voltages being fed out of U6 pin 1 are correct for the > stimulus you provided (CAL FCTR and tapping BAND+ and BAND-). Now check to > see if that (proper) 0 to 8 volt swing between pressing BAND+ and BAND- is > carried on through R19 and then through the RP2 sections and then onto the > cathodes of D16 and D17. If you get a decent voltage swing between BAND+ > and BAND- (you can expect a bit of voltage drop on the 8 volts end) at the > varactor cathodes, then look for something else wrong in the PLL Reference > oscillator (upper left of the schematic sheet - but only as far to the right > as TP3), the PLL chip does not matter until the PLL Reference oscillator is > functioning properly. > If you do get a good voltage swing at the varactors, then all I can say is > either Q19 oscillations quit when the varactor capacitance is reduced, or > there is something wrong at C84, C85, D17 or D16 which is stopping the > oscillation. If you suspect Q19 itself, you could try swapping it with one > of the J310s on the Control Board at Q6 or Q7 (these in a less-critical > audio circuit rather than being used as an RF Oscillator). > 73, > Don W3FPR Everything checked out okay, so what I think I'll do is to replace D16, D17, Q19, and the caps. Thanks again for all of the help, and I'll be back in a few days (after I get the new parts installed) with hopefully a working radio. Thanks again, John _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
