[Elecraft] KNB2 - odd behavior

[Tom Althoff]

Another more subtle side effect of the degradation of received signals by
the NB is the apparant key clicks generated by very strong signals.  Before
mentioning to anyone that they have bad key clicks it is suggested that you
check to be sure your noise blanker is turned off.  Occassionally I would
get key-click complaints on my Ten-Tec Omni-V.   I would ask the other
station to turn off his noise blanker and check my signal again.   "My" key
clicks would disappear when the noise blanker was off.

And as Dave can testify from first hand experience...a noiseblanker becomes
useless during a contest with so many 1.5KW seven element yagi CW signals
pointed at your little K2!   The TS-930 and Orion NB's both behave the same
way.   They DO work great on 160M for weak signals in winter time when the
electronic ignition of your furnace keeps zapping away all night.

- Tom K2TA
----- Original Message ----- 
From: "Vic Rosenthal" <vic at rakefet.com>
To: "David Zatopek KT5V" <kt5v at ev1.net>
Cc: <elecraft at mailman.qth.net>
Sent: Tuesday, November 09, 2004 12:47 AM
Subject: Re: [Elecraft] KNB2 - odd behavior


> David Zatopek KT5V wrote:
>
> > During SS this past weekend, I QSYed to a well-load 40 late Sunday and
> > noticed an impressive and unusual level of S9 noise.  The NB1 was on at
the
> > time of the QSY (HI THRU).  The DSP denoiser and a tighting of filters
> > helped, but the noise was pervasive and still S5.  On whim, I turned off
the
> > noise blanker and voila...no more noise (well no more than usual for my
> > neighborhood).  Turned the blanker back on...noise level back up.  No
> > difference between NB1 and NB2 and Hi/Low thru settings
> >
> > I played with this some more with the same result.  Continued with the
> > remainder of the contest.  Today, after turning the radio back on, I've
not
> > been able to duplicate the problem with any combination of NB or DSP
setting
> > tried so far.  Only difference, 40 CW is almost empty of signals here in
TX
> > tonight.  Any insights?
>
> The NB can produce spurious signals when there are loud signals on the
band.  In
> the contest, there were so many loud signals that the usual symptom -- 
sort of a
>   brapp brapp that follows the keying of the strong signal was replaced
with an
> almost continuous noise.  In order for a noise blanker to work it needs to
pick
> up signals over a wide bandwidth.  Turning on the noise blanker has a very
> severe effect on the receiver's dynamic range, which is why it's possible
to
> turn it off!
>
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
>
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