Dick, I have an 811-H connected to my K3 running 500 to 600 watts cw. I have "problems" that might be similar to yours. I get loud, fuzzy, cw tones on both my noise canceling head phones my external speakers. Both these items are powered devices. One by a wall wart and one by an AAA battery. When I turn off the headphones I get interference free audio in the headset. When I turn off the external speakers they shutdown so I have to unplug these from the PHONES jack and use the internal speaker. The internal speaker never gets the interference. My neighbors were getting the same "cw" interference on "powered" audio equipment.
I put low pass filters on both of my antenna feed lines at the output of my external MFJ-989D tuner. Perhaps I should put them between the amp and the tuner! Anyway this seemed to help but in fact it only shifted the problem frequencies from 20 to 40 meters. The low pass filters did cleanup TV interference but not the audio level problems! My next step will be to properly ground all the gear! Yes, I am guilty! In a rush to get on the air for ARRL-SS and CQ-WW I did not properly ground the new amp and tuner! I'll let you know if this fixes the problem. I had investigated chokes myself but did not want to get them until I properly grounded all my gear! BTW, the amp, tuner and K3 did well in the contests! I easily got the last 5 states I needed for WAS. All have been confirmed either by card or LoTW. I also got 8 new countries, 3 of which are already confirmed! Power helps! A lot! I let you know the grounding works out. -----Original Message----- In a message dated 12/5/2008 9:05:02 A.M. Pacific Standard Time, [EMAIL PROTECTED] writes: I'm running the K3 with an Ameritron AL800 and a Steppir 3 element with 40m dipole add-on. I have a severe though intermittent feedback problem on 40m that I did not have with an Icom 751a. The feedback only occurs when I'm using the amp (even with very low drive). I've common core choked virtually every lead with ultimately no luck. I'm using the Elecraft hand mike. Is there a known problem here? Otherwise, I'll just keep searching. Dick ++++++++++++++++++++++++++++++++++++++++++++++++++ Have you tried other bands? What Version Firmware are you using? I have a problem that may also be RF feedback related. I occurs only on 40M and only when I exceed 80 W to my Dipole antenna. No problem full power up to 120 watts into Vertical or any other band. Problem started immediately after upgrading FW to V 2.46. I have a couple upgrades to do on the rig including the AGC upgrade, which I have held off making until my Sub Receiver upgrade. Since that arrived a few days ago I will be doing all upgrades and the subreceiver install this weekend. I don't plan on any changes in FW other than activating the KRX3. I will then test the 40M issue. I do not have a good earth ground on the K3 nor am I running any form of Amp. But, the rig has worked perfectly since it was installed a year ago and the ATUs have always provided a good match in the 1.X:1 range on both Vert and Dipole including 160M, 30M, 12M, 17M in addition to the usual 5 bands the Ants are designed for. Al WA6VNN _______________________________________________ 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
