>From the K3 manual: KEY OUT (RCA/Phono) is the amplifier T-R relay keying output, capable of keying up to +200VDC @ 5A.
You do not need the buffer for any Ameritron amplifier. In particular the AL-80 schematic shows the Relay jack connected to the 12V bus. Leave the K3 key out jack connected directly to the AL-80 relay jack, and enjoy life : >) 73, Guy ----- Original Message ----- From: "Alfred Frugoli" <[email protected]> To: <[email protected]> Sent: Tuesday, June 02, 2009 9:55 PM Subject: [Elecraft] K3 Ground Loop Issues using Ameritron ARB-704 > I've just gotten my K3 built and integrated into the shack about a week > ago. Operated WPX CW this weekend with GREAT success. Was very happy. > > Tonight in setting up FSK, I was getting a lot of "AGN?" after my cq's. > Listening to my signal on a 2nd receiver, I realized that my signal had a > hum on it - basically sounded terrible. Tested in CW mode as well, and the > hum was also there (haven't dug out the mic yet for the dreaded SSB mode > to > know if the hum was there as well, but I would suspect it would have > been). > Tried changing a bunch of menu settings to no avail. Then I disconnected > everything from the back of the K3 except for the antenna, power and FSK > input. Beautiful clean signal. The hum reappeared when I connected the > amp > keying line. > > I've been using the Ameritron ARB-704 Amp Keying buffer, and even though > the K3 can handle the relay voltage on my AL-80 (the key voltage is not in > the AL-80 manual, but I believe it's 125v), I've kept in in line. However > this seems to be the item causing the hum. When I take it out of the > line, > and connect the rig directly to the amp, no hum. > > My shack is NOT well RF grounded, and things are not bonded together at > this > point (that's a needed project - but the ARB-704 doesn't have a ground > post > to connect to - I'd have to go directly under one of the case screws to > ground it). > > Anybody else experience this? Am I correct in my deduction that the K3 > key > out relay will handle the relay voltage on the AL-80? If so, I'll just > ditch the ARB-704 for now. > > Thanks. > > 73 de Al, KE1FO ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
