[Elecraft] PX3 Spike won't go away

[Phil Wheeler]

What sort of "small computer", Brian?

Phil W7OX

On 6/23/16 4:31 PM, Brian Waterworth wrote:
> In prep for field day, I decided to stage everything last night and also
> ran into the same problem as you describe.  I re-seated all the cables.  No
> effect.  I turned on the rx shft on the kx3 and the nasty noise shifted
> away.  Ok, that's good.  But not what I wanted.
>
> I disconnected the USB acc1 cable from the small computer I was planning to
> take with me to FD and the noise vanished.  Each of the computer, the kx3,
> px3, external power supply, external antenna tuner are all grounded to a
> common point.  The exception is the monitor and fan (it's going to be hot
> :-).
>
> I connected the same setup using a raspberry pi instead of the small
> computer and no noise observed at the tuned frequency.  Drat.
>
> So, I am thinking of buying a powered USB hub to try and isolate the USB
> acc1 cable plugged into the PX3.  Seems as thought the small computer I was
> going to use is picking up the internal IF and bringing it back into the
> PX3, KX3 via the USB acc1 cable.
>
> regards,
> Brian
> VE3IBW
>
> On Thu, Jun 23, 2016 at 10:58 AM, Sanger, Joseph <Joseph.Sanger at nyumc.org>
> wrote:
>
>> I have developed a new problem with my PX3, which has been quietly sitting
>> in a case for the past 6 months.
>>
>> Whenever I tune across the display, there is a slowly rising spike at the
>> base frequency (for instance, in USB mode this spike adheres to the left
>> hand edge of the bandpass indicator on PX3 screeen), takes about 2-3
>> seconds or so to increase in intensity, and then dwarfs any of the signals
>> on the band.  This spike tracks across as I tune; it is there whether or
>> not the antenna is connected.  I can tune to stations and hear them fine,
>> but the display is barely usable because of this very tall spike that won't
>> go away.  I reseated my cables connecting the PX3 to KX3, with no change in
>> behavior.  I have no other cables here to swap them out, and am kind of
>> stuck
>>
>> I have updated b both KX3 and PX3 to latest firmware, with no change in
>> behavior.
>>
>> Any thoughts would be GREATLY appreciated.
>>
>> --Joe
>> --WB2SSB