[Elecraft] Spurious

[Jim Brown]

On Mon, 21 Dec 2009 15:13:05 +0000, Ken Chandler wrote:

>I've just done some tests with my k3 sn 3759 and have been told I have  
>a spurious signal 600Hz above my tx frequency. It was at first heard  
>with my amp on but I switched out the amp and ran the k3 with 100w and  
>my note was still there.

What transmit frequency? Did you have your internal speaker turned on?  
During the recent ARRL 10M contest, several NCCC members observed spurs 
on each others signals and reported it to Elecraft. I'm told that the 
cause is acoustic coupling between the speaker and the synthesizer board, 
and that the amplitude of the spur is greater on the higher bands. 
Elecraft is intimately aware of the issue, and is working on it at the 
highest levels. 

Obviously, the strength of the spur will be proportional to loudness of 
the speaker (on TX, the sidetone setting), and can be eliminated by 
turning off the speaker. 

BTW -- one reason these spurs are more obvious is that the K3 produces 
very little phase noise to mask them. In general, other rigs (including 
many that are much higher priced) produce a lot more trash. 

73,

Jim K9YC