Mike, No, I do not believe the last digit on your measurement - call it 3.79 and be done with it - that is close enough.
Yes, U4 is the culprit here. Everything will likely work FB with the 7.88 volts, and the main thing you will observe is that the 'bogey value' AGC Threshold should be lowered a bit - my guess is: because your 8 volt rail is 0.12 volts low, you should initially set the AGC threshold so the voltage is about 0.06 volts lower than specified in the manual (set to 3.74 volts). I do recommend optimizing your AGC Threshold after you have the K2 up and running on all bands. With no antenna attached, there should be no audible difference between the AGC on and AGC off conditions (using a 0.70 width CW filter on 40 meters with the Preamp off). To achieve that, I would believe that you will end up with an AGC Threshold somewhere between 3.65 volts and 3.70 volts - but that remains to be seen for your particular K2. Further refinements/adjustments are possible, but I cannot go into all the details in a reasonable length reflector post. If you want to do this optimization, the goal should be to achieve a condition where the receiver gain is not reduced by internal receiver noise while retaining 'good' S-meter activity (the CAL S-LO and CAL S-HI setting interact with the AGC Threshold and can create a lot of work if you choose to 'get it just right' - and what is 'right' is subject to individual interpretation). 73, Don W3FPR > -----Original Message----- > > Thanks very much, Don, for your ideas. My email had faulty numbers as a > result of a faulty (human!) memory. I remeasured voltages just now at > Control Board locations you measured and got these results: > > - U2 pin 5: maxes out at 3.792 V if you believe that many > significant figures. > > - P1 pin 6: 1.2 mV > > - U4 OUT: 7.88 V ... the culprit? > > I will disassemble and check my solder connections you mentioned. > > Thanks and 73, > Mike AB3AP > Avondale, PA > > >>from Delaware once I make a portable dipole for 20m. Maybe another > >>month, plus or minus a little. In my year and a half on the air as a > >>ham I've never checked into a CW net, though, so that'll probably be an > >>adventure itself! > >> > >>Mike AB3AP > >> > _______________________________________________ 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
