http://elecraft.85.s1.nabble.com/P3-SVGA-interference-tp7556731p7556742.html
There is (was) a known problem with the MMIC amplifier (comprising the IF amp
into the P3) oscillating.....this instability could certainly manifest itself in
what you are seeing.
The guys at Elecraft sent me a replacement rear panel interface board and my prob
the supplied star washers.
>Is it possible the ribbon cable is as long as it is because it will need to
>eventually be routed around something else to be added later?
>
>Art - N4PJ
>
>
>
>On Tue, May 29, 2012 at 2:10 AM, Bob Lanning
[hidden email]>wrote:
>
>> In response to my message May 23, 2012; 3:27pm on the Elecraft P3
>> reflector Roger White W5RDW in Murphy, Texas responded off-list. He had
>> the same problem I described. It was not coming from the K3 but from
>> inside the P3. We both noted it started after installing the SVGA.
>>
>> During our investigation we boy found:
>>
>> 1 - the signal is about 5kHz wide
>> 2 - it moves either up or down in frequency ever so slowly
>> 3 - moving the VFO does not change the position of the signal - internal
>> to P3?
>> 4 - reach back and approach the IF signal coax between the K3 & P3
>> causes it to temporarily go away
>> 5 - sometimes touching the P3 cabinet caused it to disappear
>> 6 - changed out the coax but it still happens
>>
>> When the signal crosses the VFO frequency no sound is heard - only the
>> signal being listened to. But reaching back in the proximity of the
>> linking coax causes it to go away. Turning PC and other gear off has no
>> effect.
>>
>> Roger and I spent sometime isolating the source. We found a signal was
>> coupling into the IF cable inside the P3 from the ribbon cable. As you
>> can see from the SVGA instruction manual the ribbon cable is so long
>> that if not dressed it goes across the P3 and pushes up against the IF
>> coax in the unit.
>>
>> When the ribbon cable is dressed by folding it tightly keeping it well
>> away from the IF coax the wondering signal no longer appears.
>>
>> If you are having this anomaly Roger and I recommend making the change
>> to the ribbon cable as shown in the two pictures below. It would be
>> nice to have a shorter ribbon cable.
>>
>> 73,
>>
>> Bob - W6OPO
>> Roger - W5RDW
>>
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