When you switch from CW to SSB are you also changing frequencies from the CW subband to the SSB subband? If so, repeat your test on the same frequency. My simple world view makes this one easy to solve. Stay on CW :-) - Keith N1AS - - K3 711 -
________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of G4MKP Sent: Friday, October 17, 2008 10:47 AM To: [email protected] Subject: [Elecraft] ATU Flashover Problem on 80m SSB. I am experiencing what I can best describe as ATU Flashover on 80m SSB. Background - I have a K3 and Challenger 3 linear amplifier. Headgear is the Heil Proset plus. I can tune up the rig and amp to well in excess of 500W without any problem. CW can be operated at full power without any problems. However, when I modulate the radio using SSB on 80m at anything above approx 275W, the SWR goes from 1:1 to infinity and I can hear the ATU flashing over. It also occurs when modulating the radio using AFSK for RTTY operation. Opening the ATU reveals arcing between the capacitor plates. The problem does not occur on any other band. Grounding - all equipment is individually wired to a central rf earth point which is connected to a buried copper earth rod. I have a further 4 copper rods connected to the previously mentioned rod that are spread over a few feet. Antenna - 80m inverted L with six radials spread over about 45 degrees. I don't have another rig at present to substitute. Any idea what's going on please? Cheers, Terry G4MKP
_______________________________________________ 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
