[Skimmertalk] Preamp and clipping issue?

[Rick Kiessig]

I'm using a QS1R with a Clifton Labs Z10040B preamp.

 

When I run SDRMAX with the preamp in-line, the receiver's clip light blinks,
and the waterfall display shows what looks like broadband / all-band noise
flickering quickly on-and-off. If I remove the preamp, the patterned noise
goes away.

 

When I switch to using CW Skimmer or Skimmer Server instead, the clip light
doesn't blink anymore. CW Skimmer still shows a similar pattern of noise /
artifacts, though. The waterfall there shows what should be steady carrier
signals being broken up by the noise to the point where they almost look
like Morse.

 

The overall system seems to be working OK, in that I'm seeing about 50% more
spots with the preamp than without. However, I'm wondering if I might be
able to improve things further by cleaning up the signal.

 

I'm suspicious that clipping is still happening when Skimmer is running.
Does the clip light still work with the FPGA code that's loaded by Skimmer?

 

I'm wondering about adding a high-pass and/or low-pass filter to try to
clean up the signal. Does the QS1R produce a distinctive noise pattern in
SDRMAX or CW Skimmer when it goes into clipping mode? Or is there another
way I can tell if the front-end is getting overloaded?

 

73, Rick ZL2HAM