Lyle I suspect that the spike at zero has to do with the fact that the radio is direct sampling and the IF is zero. Elecraft has built in an at least a partial fix, the 8 KHz. receiver offest. That has helped at my place. The second that added a little bit is a galvanic isolator I picked up at Radio Shack for about $10. It didn't totally remove the "spike", but it did knock it down a bit.
73, Barry K3NDM ----- Original Message ----- From: "Lyle Johnson" <kk7p4...@gmail.com> To: "k7nhb" <desig...@quickdata.com> Cc: elecraft@mailman.qth.net Sent: Monday, April 1, 2013 8:50:35 PM Subject: Re: [Elecraft] NaP3 and the KX3 Paul, Usually the "big center spike" is due to a so-called ground loop between the computer_plus_soundcard and the KX3_plus_power source. The two ways to cure this are: 1) bond everything together with low-resistance, low-inductance straps, or 2) use audio isolation transformers. There have been lots of posts here about candidate isolation transformers. I have no idea what the "two side traces" might be. How far apart are they from the center spike? Are they symmetrical on either side of it? What is their amplitude? Do they get masked by band noise when you have a tuned-up antenna attached to the radio? Apart from the three spikes, is the panadapter otherwise working on your computer? 73, Lyle KK7P > I've been struggling with HDSDR and a Griffin audio device to bring the audio > from the the Elecraft RX I/Q cable in via USB. I get a big center spike in > the display with two side traces. ______________________________________________________________ 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
