This is a common problem with DXDoubler due to differences in chassis potential between transceivers. TopTen Systems have even published an application note concerning the issue: http://www.qth.com/topten/apnote9.htm
Their solution, as you have already discovered is to add two transformers in the headphone line between one of the transceivers and the DXDoubler. The recommended transformers will have approximately 3 dB of insertion loss ... it will be necessary to "turn up the volume" on the transceiver with the transformers in line. 73, ... Joe, W4TV > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of > k...@baymoon.com > Sent: Monday, March 15, 2010 4:41 PM > To: elecraft@mailman.qth.net > Subject: [Elecraft] DX Doubler/K3 issue > > > Just completed my second K3/100 and am in the process of > integrating them into the former FT-1000 SO2R station. I'm > using the DX Doubler for SO2R switching. I bought the K3 > cables from them, and hooked up both radios to DXD. When I > plug the headset into the DXD phone socket, I hear a hummy > sidetone and low-level hum on both radios. With a headset > plugged into either the front or rear K3 phones sockets, I > don't hear it. So, it sounds like something that's occuring > as a result of whatever's going on inside the DXD. For now, > I'm planning to isolate the audio output going to the DXD > using 1:1 isolation xfmrs. But has anyone else had a similar > problem? If so, how did you cure it? > > I had a similar problem (and used the same solution) with the > FT-1000s and the DVD. I thought it was a Yaesu issue, but > maybe not.... > > Rob K6RB > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
