G'day,
1. Both birdies in #1400 are at the LF band edge of 10M one is from the
K2 MCU clock the other is from the KPA100 processor clock. The latter can
be put where you wish depending upon your priorities, no birdie at the top
end of 75M or no birdie at the bottom end of 10M, take your pick. See
KPA100 receiver tests, last point.
2. No birdie at 28020
3. KNB2 on #1400 works very well in my environment. Pulse noises from
electric fences vanish. Broadband pulse junk from a faulty sodium vapour
street lamp that is S9 on 160M vanishes. Not quite so good with the same
source on 30M.
I've no complaints.
With apologies I will copy the following post from October 2000:
<quote>
Thought I'd add my two (binary) bits worth to the NB discussion:
I find that my NB is very effective on an annoying popping sound (mostly
on
80M) that I suspect is caused by an electric fence in the area. NB1
reduces
it considerably and NB2 removes it completely. I get similar results for
certain types of static crashes: NB1 is somewhat effective and NB2 is very
effective. However, neither seems to be too effective against electrical
noise from drill motors, etc.
Back in August a couple of folks posted notes that they had increased C12
on the NB board by a factor of 10 to 20 (thus increasing the blanking gate
width to around 1-2 milliseconds) and got much better blanking of
electrical noise. So I decided to give that a try.
Increasing C12 to 0.1uF definitely resulted in better attenuation (with
NB2
selected) of some types of electrical and atmospheric noise. However, it
resulted in a rather raspy sounding CW signals. Backing off to 0.047uF
worked just about as well on noise and did not produce any noticeable
effects on signals.
As a result, I have made the following mod to my NB board:
1. Changed C11 from 0.001uF to 0.0068uF (using the original C12 cap) to
give an NB1 blanking pulse width of 65-70 us (instead of 10 us).
2. Changed C12 from 0.0068uF to 0.047uF to give an NB2 blanking pulse
width
of around 500 us (instead of 70 us).
Seems to be a good overall compromise for the types of noise that I hear.
Your results may vary.
72/73,
Larry W1HUE/7
<unquote>
Regards,
Mike VP8NO
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