Clicking and Thumping in the Passband During CW Contesting with my 6600M

Al Dewey

I have used my new 6600M in a few contests now and really like it.  I have noticed one thing, however.  When I am running on CW with the filter set at 250hz, I sometimes hear clicks and thumps inside the filter passband.  It sort of sounds like key clicks or products from another strong signal elsewhere in the band.  It comes and goes but, when it comes, it can wipe out the signal in the passband.  Is this normal or do I have something not set right?   I have NB and NR on at about 30%.  I have RF gain at zero.  AGC is at about 50%.  FDX is on. Binaural Audio is enabled.

During normal operation (i.e. outside a contest when there is not a lot of activity on the band), I never hear this.

Does anyone else ever notice this?

73,

Al, K0AD

Duane_AC5AA

First, try turning the NB off.  Second, a nearby transmitter with key clicks will also cause this - not much you can do about that.  I'll leave more elegant solutions to others!  Hope this helps.

Tim - W4TME

I'd turn both the NR and NB off.  Rarely do you experience a complex noise signature that requires both.  Properly using the AGC-T and setting it for maximum SNR based on band conditions (noise floor) will reduce a lot of natural noise.  An AGC-T setting of 50 is probably the upper-end setting for the summer.  For example on 6m, mine is set between 25-30. How to set it is covered in the SmartSDR Software Users Guide. The only time I need to use DSP noise mitigation is at Xmas when the Xmas tree lot across the road turns on their halogen lights; WNB wipes it out. 

When you use the NR, NB or WNB, the DSP needs to train on the received signal in an attempt to mitigate the specific types of noise sources; periodic noise for the NB and random noise for the NR  If this type of noise does not sufficiently exist, it is more challenging for the DSP to operate on it and that can occasionally result is a pop or click.

Al Dewey

Thanks Duane and Tim.  I'll tweak the AGC a little and turn off NR and NB.  Next big test will be IARU in July.....de Al, K0AD

ctate243

Also in contest conditions use the WNB sparingly..  usually best to leave it off.

Paul KB3ML

One other thing you may be hearing is the Phase Noise of adjacent signals. It can be seen by the sloping sides of  their envelope.
Although you may not be hearing the tone, you will hear the noise. This is  because of the superb sharp filters in the Flex.  Radios with crystal filters just don't have that kind of selectivity.

TNX Flex !

Tim - W4TME

+1