On Sun, 5 Sep 2010 17:55:15 -0600, W0SZ wrote: >Has anyone installed the K3 Synthesizer Stiffener Plate Mod? Do you think >this is an important Mod to install in an old K3?
If you transmit CW, RTTY, or PSK with the speaker on, vibrations from the speaker can modulate the synthesizer at the frequency of your sidetone. This produces sidebands that differ from your main signal by the sidetone frequency(ies). This can be VERY serious -- it is a violation of FCC Rules, it causes QRM, and it leads to confusion. Several of us who are members of NCCC (Northern California Contest Club) learned this the hard way last winter during the 10M contest, when we were getting off-frequency responses to our CQs! Mostly contesters and CW ops use headphones, but the 10M contest is one where you must call CQ for hours on a dead band with no responses, hoping for a band opening. During that time, you do things around the shack, etc., listening on the speaker. Many of us also use the speaker when working RTTY during contests. The band-aid fix for the problem is to use an external speaker that you move away from the radio. So the short answer is that if you work CW, RTTY, or PSK with sidetone Monitor into the internal speaker turned on, this mod is VERY important. 73, Jim K9YC ______________________________________________________________ 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
