+++++++++++++++++++ See also Signal Tracing +++++++++++++++++ Date: Sun, 9 Dec 2001 09:40:44 -0600 From: "Jay Henson" Subject: [Elecraft] K2 Signal Tracing Tom and the group, I was asked by a friend to look at his K2. It seems that the rig had low (very little) audio. The audio was there but could barely be heard, even with the audio control at max. I remembered Tom's article on signal tracing the K1 and K2 so I dug it out. The rig had low audio on ALL bands and I knew it had worked at one time. We had used spectrogram to align his filters. A gut feel told me the problem was downstream of the LPF's and BPF's. The attenuator selection did attenuate the input signal. Selecting/deselecting the preamp did produce a change in the signal level. Again, a gut feel told me the problem was downstream of the RF preamp. The sidetone level was loud and changeable from the menu and the volume control caused change in the audio level (what there was of it). Gut feel said the problem was upstream of the audio amp. Tom's article on signal tracing started at the TUF-1 and worked back to the antenna. What the heck. I tried his method at the product detector and IF amp. 4.915 mHz is still in the RF region. There were signals to be heard. Very weak but there. As I worked back through the crystal filter, the injected signals seemed to disappear. Rule #1 - Make the basic radio work first so I removed the SSB adapter and added the W2/W3 jumpers. Now there is plenty of audio. To make this long story short, the input side of the SSB adapter had a bad solder joint. The important thing I found was that Tom's signal tracing technique can be used in the IF sections also. The signals will be weaker as there is very little amplification but the signals CAN be heard. Many thanks for the technique, Tom. My best to all! Jay AJ4AY Mobile, AL FP -115, SOC 220, ARCI 8131, FISTS 7917 K2 # 1073 ++++++++++++++++++++ Date: Sun, 09 Dec 2001 21:58:54 -0600 From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: [Elecraft] Re: K2 Signal Tracing Jay: >The important thing I found was that Tom's signal tracing technique can be >used in the IF sections also. The signals will be weaker as there is very >little amplification but the signals CAN be heard. > >Many thanks for the technique, Tom. My best to all! Thanks to YOU, Jay, for a bit more insight into troubleshooting the K1/K2! APPRECIATED! Season's greetings, Tom N0SS ++++++++++++++++++++ Reply-To: From: "Tom Crites" To: Date: Tue, 18 Jun 2002 22:53:14 -0400 Subject: [Elecraft] K2 Signal Traces PDF file I've created a PDF document showing a number of traces from my K2 at various points along the signal path. I figure this would be helpful for troubleshooting and/or educational purposes. I'm hoping some of you might take a look at what I've come up with and give me your thoughts. The document can be found at the following link (sorry about the format, but least you can get the file). http://home.attbi.com/~crites/wsb/html/view.cgi-home.html-.html Thanks, Tom, KC8SES Crites at iname.com +++++++++++++++++++++++ To: elecraft at mailman.qth.net From: thomas.crites at gm.com Date: Wed, 18 Sep 2002 12:09:51 -0400 Subject: [Elecraft] K2 Signal Traces Eric has recently added my "K2 Signal Traces" document to the Builder Resource Page, of the Elecraft website (www.elecraft.com). I'd like to= invite everyone to take a look and let me know of any improvements that= they would like to see (additional traces, measurements, descriptions,= etc.). From some of the recent activity on the reflector maybe some a= udio frequency traces would be in order. :-) Can anyone tell me what's going on in figure 16, with the signal superimposed on the main waveform? Thanks, Tom, KC8SES crites at iname.com ++++++++++++++++++