[Elecraft] ***K3 Spurious Problem Alert***

[Bill Tippett]

On 2 nov 2009, at 12.02, Bill W4ZV wrote:
>
>  Two Topband buddies have now reported a bad spur with relatively new K3s
>> (April or May 2009) at only 20 dB down about 16 kHz from the fundamental.
>>
>
2009/11/8 Björn Mohr <bjorn.mohr at gmail.com> wrote:

>
> I found it useful to fiddle with the routing of the coax cables from the
> synthesizer modules to minimize the level of spurs. It won't completely
> remove them, but at least it improved the situation. I have an early K3 in
> the serial # 200 range and many spurs where introduced when the sub RX was
> installed.
>
> I know I have at least one spur on topband that I have "masked" using the
> signal remove function. As I am travelling I cannot check the frequency of
> it right now.
>

Björn, just to clarify, the 16 kHz spur mentioned above is **NOT** a RX spur
but a **transmitted** spur.  This is caused by an extra capacitor on the
KPA3 board which should have been removed in production.  This spur is not
caused by cable routing as is the case for some RX spurs.  This problem
affected ~50 units in the range of S/N 3000 and produced in April/May 2009.
Elecraft attempted to contact the owners of these units but apparently a few
did escape.  It just so happened that two of these were good Topband friends
(AA1K and K3ZM) who bought their K3s on my recommendation.

If your K3 is near S/N 3000, I would strongly encourage you to have someone
check that your unit is not transmitting a strong (-20 dB) spur ~16 kHz from
the fundamental.  The solution was described in my original post and is
relatively easy to implement.

73,  Bill  W4ZV