Greetings Sarah, welcome to the hobby, and to a great radio. My AGC measurement was down a bit, not quite as far as yours, but it has been discussed here that there is some variation, and that it is not critical at that point. I re-visited my a little later on in the build process, and the numbers came up some.
Don, W3FPR, has given some good explanations for why this is, I just don't recall them at the moment. A quick search of the archive; http://www.mail-archive.com/[email protected]/maillist.html Here is one example of what I found; http://www.mail-archive.com/[email protected]/msg01791.html So I don't think your measurement is at a critical level at this time. Don, or others will likely help with further information. Best of luck to you, and enjoy the build. It really is a fine radio. 73 - David Wilburn [EMAIL PROTECTED] K4DGW K2 S/N 5982 On Fri, 2007-11-23 at 12:53 -0800, Sarah K. wrote: > Hi, > > I'm Sarah, AF6FH! I just got my license a couple weeks ago, and I'm > now assembling K2# 0622, which will be my first HF radio. I started > assembly on Wednesday night, and so far, everything's been going just > fine. > > But... > > I'm having a little issue with setting the AGC Threshold. > > The instructions (pg. 48) say to set the RF GAIN control fully > clockwise, measure the voltage on pin 5 of U2 on the control board, > and adjust trimmer R1 for a reading of 3.80 volts. > > I did my voltage measurements with my own (cheap) DMM, not the > internal voltmeter. > > My concern is that, by adjusting R1, the highest I could get the > voltage to go was 3.59v, so for the moment, that's where it's set. > > I measured the voltage on the LM29307-8, and it has 12.23V at the > input, but only 7.53V at the output. The 78M05 has 4.93V at its > output. > > When I rotate the AF GAIN control, I get a range of 4.68V (fully > counter-clockwise) to 3.59V (fully clockwise) on pin 5 of U2. > > My power supply is a small benchtop power supply; it's putting out > 12.4V, and reports the K2 is drawing about 100mA. When I measure the > input voltage across the K2 input jack, I get the same 12.4V. > > All of the previous checks were fine, and the following step, S-Meter > Alignment, seemed to work just fine. > > So, my question is, do I have a problem? Should I be concerned? > > Thanks, > > Sarah AF6FH > _______________________________________________ > Elecraft mailing list > Post to: [email protected] > 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 _______________________________________________ Elecraft mailing list Post to: [email protected] 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
