On Mon, Dec 08, 2008 at 11:45:07AM -0600, Charles Bibb wrote:
> A good noise blanker works wonders on this pulsed type noise, making
> the weak signal readable - that is until a strong US station or
> stations (pileup) starts up nearby. Then the noise blanker might as
> well be off. And, the strong station(s) doesn't have to be
> particularly close - 10khz or more at my QTH. Frequently, while
> listening in the early morning for weak JA's with the NB on, I can
> hear multiple CQDX's of keyed wideband noise - my noise floor being
> pumped by STRONG US stations.
There are two issues here. If there is a strong signal in the passband
of your "roofing" filter then it can desense your noise blanker and it
can no longer work on the noise.
However, a second problem is that when your noise blanker does blank, it
actually will modulate those same signals with a sharp edge and make the
signals sound clicky. I proved this to myself once by using two TS850s
and had the noise blanker active on one outside of the band - and had it
triggering the NB gate in the radio tuned to the strong signals. I had
a bunch of clicks being generated by the NB rapidly turning on and off
the switch. You need to have some smoothing done to avoid this problem.
I have recently upgraded to a K3 and one of the features that really make
me love this radio is its ability to deal with this type of noise within
the passband of a narrow roofing filter. I typically use the 400 hertz
one and this radio can deal with the electric fences around me just fine.
I believe it can also do a good job on power line noise.
So - if you know someone who has one - you might see if you can borrow
one and try it with your noise.
73 Tree N6TR
Boring, OR
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