Weird problem with NB - works as AM detector

[sp5it]

Hi. I got the problem with one radio.

When NB circuit is on I can hear stations talking on the other channels in a few hundered meters radius weak but clear - nor dependent on rfgain position. It is working as AM detector.
When NB is off they are gone.
Anyone had similar issue? Ths NB circuit is very common for most SSB chassis.
How to get rid of that?
I tried to use diffrent D1, D2 diodes but no improvement.
Mike

 

[Shockwave]

Because the noise blanker compares the average noise around your frequency to the noise on the actual frequency to determine if blanking is triggered, they often have problems dealing with strong signals. Strong on frequency signals can sometimes be distorted and strong adjacent signals can "bleed" right trough the noise blanker. The better circuits have an adjustment to set the blanking trigger level. I didn't see that in your schematic but it sounds like the blanker may be too high. In either event I wouldn't expect good NB performance with adjacent stations transmitting within a few hundred meters of you.

 

[sp5it]

Can you point me to the schematic with NB trigger adjustment? Maybe I could modify circuit in my radio.
Mike

 

[JoeDirt]

You sure no one installed funnies on that switch?

 

[sp5it]

Nope. Radio is stock.
Mike