Stephanie, Congraulations on finding the source of your PLL problem - those intermittents can be quite nasty to find.
It is likely that your low 8 volt regulator is causing your lower AGC Threshold. Actually I would recommend not worrying about it at this stage - but just make a note of it. Later, you may want to optimize the AGC Threshold so there is little or no difference in the receiver gain between AGC on and AGC off (with no antenna connected) - and that condition will assure you that the AGC is not reducing the receiver gain when there is no signal present. The optimum setting in my experience is between 3.65 and 3.8 volts, but it does vary from K2 to K2. The actual voltage on the 8v line will make a significant difference on the voltage available at the AGC Threshold measurement point. BTW - with the 8 volt regulator at 7.8 volts - that is only 2.5% less then the nominal voltage, so the regulator itself is operating within its spec even though that voltage is a bit lower than usual. 73, Don W3FPR > -----Original Message----- > > Well I finally got the PLL reference oscillator to oscillate > consistently. > > I removed the crystal and found a tiny little sliver of metal > shorting one of the pins to the case. I don't think it was solder as > it wouldn't melt but I was able to pick it off with tweezers. I also > re-seated D18, it was sticking up just a little and might have been > shorting against the hardware that holds the 'foot' to the case bottom. > > After that, I was able to complete the Alignment & Test #2. Tomorrow > I'll start on part 3 of the build. > > I did find one other thing that doesn't seem quite right. I'm having > some trouble with the AGC circuit, and adjusting R1 on the control > board. It says to adjust R1 to see about 3.9 volts on pin 5 of U2, > but I can't get any more than 3.7 volts. Turning R1 through its full > range, I go up to 3.7 with about 75% rotation, then the last 25% it > just stays at 3.7 volts. I don't know if this could be a problem > later. I'm reading 7.8 volts on the 8v line so it might just be that > the 8v is a bit low. > > Thanks again for all the help everyone! > > 73 de Stephanie > va3uxb > > _______________________________________________ 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
