[Elecraft] K3 Synthesizer Stiffener Plate Mod

[Jim Brown]

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