Receiver desensitized

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billjhs
Posts: 1
Joined: Mon May 22, 2017 11:33 am

Receiver desensitized

Postby billjhs » Mon May 22, 2017 11:44 am

Hello all...have had the sdrplay rsp2 for a month now and totally enjoying using it..I have a w6lvp loop antenna hooked up (which works great) and use it to monitor the ham bands instead of using my kx3 (sdr has multiple receivers)....only problem I am having is when a ssb or cw sig is within 300 khz and they are over s9 +20db it makes the whole band go up and down...I have a guy on 75 meters that is 30 over and he bumps my receiver...tried different settings of gain, etc....only thing that helps is reducing the bandwidth of the receiver so the sig isn't in the "passband"....anyone else experience this?

73
Bill
Last edited by billjhs on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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g1hbe
Posts: 240
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire

Re: Receiver desensitized

Postby g1hbe » Mon May 22, 2017 1:48 pm

It's inevitable really. The AGC has to keep everything within the passband below the clipping level of the ADC or there will be severe distortion, intermod etc. So if there's a very strong signal anywhere in the selected bandwidth, the gain will reduce to accomodate it. As well as reducing the bandwidth to exclude the offending signal, you can try reducing the gain manually which should reduce the effect.
I suppose this is one of the downsides of having a huge 'visible bandwidth'!

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Andy

W2DLC
Posts: 41
Joined: Tue Apr 04, 2017 1:51 pm

Re: Receiver desensitized

Postby W2DLC » Mon May 22, 2017 5:09 pm

Did you try using the notch filter to notch him out? Also, there is more than one AGC control. I don't even turn on the LNA on the HF bands and I set the base AGC level in the EX control window to about 90, but will move it up and down as necessary. Sometimes I also turn off the main AGC and manually set the level. There is also an IF AGC, which I rarely mess with, but it may help in your case. That is in the RX window settings.

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