SSDR and 6400 Noise Floor Behavior

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  • Problem
  • Updated 2 years ago
  • In Progress

Odd SSDR Behavior


1.       Flex 6400 – heatsink upgrade not yet done

2.       Windows 10 v 1803

3.       SSDR 2.2.8

4.       Antenna Dipole (40m)



1.       Slice A on 15m WNB off-   21.026.220 Mhz - -124dBm (or any in band freq)

2.       Slice B on 40m WNB off- 7.038.330 Mhz - - -106 to -112dBm (or any in band freq)

3.       Preamp +8dB (tried at 0 and -8 and has no effect on the scenario)

4.       Bandpass is WIDE

5.       Turn Slice A WNB on-set at 30,  Slice A remains at -124, Slice B remains at -106 to -112

6.       Turn Slice A WNB off - - Slice A jumps up to -115, Slice B remains at -106 to -112

Slice A is active, tune Slice A to 21.026.230 (10 hz up) using the Flex Knob---- NOW Slice A drops back to -124 dBm (WNB is OFF – both slices) This is repeatable and seems to occur whenever Bandpass is WIDE and occurs with Slice A on 10, 12, 15, 17, 20, 30 (barely noticeable), 40 (smaller jump in level), 80. This does not occur when both slices are on the same band and front end filters are engaged (i.e. not WIDE)

Reversing slices the above steps and Slice B behaves similarly. 

Connected to Dummy load – same scenario behavior

No RELAY clicks other then when band is intentionally changed.

I have a video of one scenario – sorry for a bit of shake holding the iPhone.

If this is expected or my test is faulty I apologize for the bandwidth.  Anyone should be able to replicate this behavior unless it is my 6400 or my SSDR install.  This seems different from the behavior described by Mike (“6600 odd behavior” 2 months ago). 

There are a lot of variables and possible scenarios and I have tested only a few.

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N5LB - Lionel B

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  • Very Curious

Posted 2 years ago

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Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

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Since this indicates you may have a hardware issue and issues of this type are not resolved using the Community, I have converted this topic to a support HelpDesk ticket ( for expedited issue resolution.  Please respond using the HelpDesk ticket rather than the Community.
Photo of N5LB - Lionel B

N5LB - Lionel B

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Thank you Tim.