Hi David and Vic; David in addition to Vic's suggestion you might want to check the input circuit on each band with a grid dip meter to confirm the settings. If bad, look at the slugs in the input coils (if used) for cracks or breaks or check the compression Caps (if used) for proper operation.
Is the grid current the same on all bands, proper output or not? Vic is on the money with input switch problems.. check the contacts. Clean them and check them again. gl, pete -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Vic K2VCO Sent: Tuesday, June 27, 2006 7:52 AM To: David Douglass Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] Slightly off top amp question David Douglass wrote: > Apologies in advance for the off topic question! > > I've just bought an old FL-2100B amp to do up, and run with my K2 (I have > the bits and pieces on order for the external keying circuit!!). > > When trying the amp out I found that I am getting a pretty high input SWR, > and thought I should Align the input coils on the amp. > > This seemed to work OK on 40m, and 15 and 10m are not too bad (~2:1), but I > have a very high input SWR on 80 and 20 irrespective of where I tune the > slugs. > > It looks like the valves in the Amp are the original Centron 572B/T160's, > which are lighting up, but are obviously very old (>20 years I would > imagine). > > If the valves were on the way out, could this account for my inability to > tune the input coils, or should I look elsewhere for the problem ? Are you getting reasonable output on the bands where the SWR is OK? If so, then the problem is not the tubes (valves). Check that the bandswitch is indexing properly. Also, a problem in the output tank circuit can cause a high input SWR -- look very carefully at the bandswitch contacts to verify that they are not burned and are indexing correctly. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ 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 __________ NOD32 1.1627 (20060627) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com _______________________________________________ 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
