Panadapter goes blank when pre-amp enabled

  • 1
  • Problem
  • Updated 11 months ago
Flex 6600M running SmartSDR v2.4.9, Windows 10

I have a repeatable problem where the panadapter display goes blank whenever pre-amp selection is greater than 0dB (default).  Selecting any of the other positive gain settings (ie, +8dB, +16dB, +24dB or +32dB) will cause the panadapter to go blank (see picture).  The panadapter display can be restored by selecting -8dB or 0dB settings.  When the panadapater does go blank, the waterfall is still fully functional and the receiver seems functional in every other way.

Any ideas?


73, Grant K1KD


Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes

Posted 11 months ago

  • 1
Photo of Michael Walker

Michael Walker, Employee

  • 1346 Posts
  • 394 Reply Likes
Hi

Your receive antenna is set to the to RX A. Is that the antenna you wish to use?

Mike
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
Hi Mike.  Yes, ANT1, ANT2 and RX A are all valid antenna selections for me.  The panadapter issue is present regardless of antenna input selection.
Photo of Gary NC3Z

Gary NC3Z

  • 175 Posts
  • 37 Reply Likes
Have you tried to move the slider  on the right side of the spectrum to rescale it to more than -140dB? 

As you apply pre-amp gain you will see the spectrum floor go down.
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
Gary,
Great idea!  I think your suggestion is on the right track.  Typically, I have the minimum amplitude on the panadapter adjusted so the noise floor is positioned near the bottom of the screen.  For example, on 6m with pre-amp off my noise floor is -130dB so I have adjusted the vertical axis slider so the minimum amplitude is approximately -140dB.  Now, if I switch to +8dB pre-amp selection, the panadapter goes completely blank as previously reported.  But,  if I adjust the minimum amplitude all the way down to -170dB, I can still see just the peaks of strong stations.  Anything selection greater than +8dB pre-amp and it is totally blank.

As you say, the pre-amp does indeed cause the spectrum floor to go down.  However, in my case it appears to go down so much that it renders the panadapter useless.  Is this the way it is intended to work?  Anybody else see the same thing?
Photo of KC2QMA_John

KC2QMA_John

  • 867 Posts
  • 389 Reply Likes
You may have a bad RF preamp or loose connection.
May have to go back to flex.
Open a Helpdesk ticket.
https://helpdesk.flexradio.com/hc/en-us/?_ga=2.75158930.1231518986.1562282613-515553593.1552398895
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
John, thanks for the comment.  Even though the panadapter noise floor is dropping below the panadapter minimum when the pre-amp is enabled, the waterfall display is fine.  This leads me to believe there isn't any physical problem with the radio (ie, bad RF preamp or loose connection).  It just appears that something is throwing the panadapter scale way off when pre-amp is on.
Photo of Dudley - WA5QPZ

Dudley - WA5QPZ, Elmer

  • 277 Posts
  • 49 Reply Likes
Grant,

Try clicking on the vertical scale on the right side and move up, so you will expose more of the scale, this is most likely where your horizontal panadapter is hiding.

Dudley
WA5QPZ
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
Hi Dudley, the panadapter noise floor with no pre-amp is -130dB for me right now.  Everything displays fine.  But, with just +8dB pre-amp, the noise floor on the panadapter display goes below -170dB.  All I can see is the peaks of signals (see picture).  I can't slide the vertical scale low enough to see the noise floor.  Also, note that the waterfall display is working just fine.
Photo of N8SDR

N8SDR

  • 201 Posts
  • 31 Reply Likes
click the  arrows on the right side of the scale were it currently list -100 -110 -120 etc. drop that downward. and you should be good. if it doesn't move, then try doing a factory reset , dont forget to save your profiles before doing so, then if that works you can import them back in.

(Edited)
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
Hello, yes I am able to click the up/down arrows in the top right corner of the panadapter to increase/decrease the maximum amplitude.  I am also able to adjust where the noise floor is positioned within the panadapter by clicking/dragging the vertical axis.  All that works fine.  What does not seem to work correctly for me is the amount the noise floor shifts with different pre-amp settings.
Photo of Cal Spreitzer

Cal Spreitzer

  • 455 Posts
  • 116 Reply Likes
What happens if you zoom out the waterfall to Wide?  Any change in noise floor then? 

Cal/N3CAL
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
Hi Cal, thanks for the suggestion.  I tried zooming out the waterfall to wide, but the noise floor was unchanged.
Photo of Michael N3LI

Michael N3LI

  • 248 Posts
  • 82 Reply Likes
Out of curiosity, try turning off your spotting software. I don't think this will matter, but maybe.

Also, you might try resetting the radio. The waterfall looks great, but hard to imagine the pan being that wonderful quiet.
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
Hi Michael, I tried turning off the spotting software, but that did not make any difference.  I think I will try doing a factory reset of the radio this evening.  I'll report back with results.
Photo of Bill -VA3WTB

Bill -VA3WTB

  • 4586 Posts
  • 1091 Reply Likes
Looks like he is moving the wrong scale. It is the one above the water fall.
Photo of Michael Walker

Michael Walker, Employee

  • 1346 Posts
  • 394 Reply Likes
Another question.  What happens if you select ANT1 as the receiving antenna?  Does it work as you would expect?
Photo of Bill -VA3WTB

Bill -VA3WTB

  • 4586 Posts
  • 1091 Reply Likes
What happened when you did a factory reset to the radio?
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
I'll give that a try, Bill.  Thanks for the suggestion.
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
Hi Michael, up until this evening I would have said the receiving antenna selection makes no difference.  However, I've been doing a lot of experimentation and here is some data I have collected.  This is my noise floor on 10m band as measured off the panadapter with different RX ANT and RF Gain selected:

PreAmp  RX A    ANT1    ANT2
-8dB       -117     -117     -117
0             -124    -124     -125
+8dB       n/a      -131     -132
+16dB     n/a      -134     -136
+24dB     n/a      -137     -140
+32dB     n/a      -138     -140

ANT1 = Dipole
ANT2 = Beam
RX A = Loop

The measurements that were 'n/a' were off the bottom of the display.

I want to say that I've had different results in the past where ANT1 might exhibit the issue while ANT 2 or RX A were fine.  However, at the moment this is what it is giving me.  For the time being, these results are repeatable.  73, Grant
Photo of Grant Kesselring

Grant Kesselring

  • 42 Posts
  • 0 Reply Likes
I just tried my experiment again, this time on 30m.  Now, the panadapter noise floor is shifting below -180dB when the PreAmp is +16dB, +24dB or 32dB.  This is happening with ANT1, ANT2 and RX A.