[Elecraft] noiseblanker

[Evert Bakker (PA2KW)]

Hello Arie,

I can confirm that the noise blanker does not work at all with electric
fence pulses. Unfortunately I experienced that the noise blanker is very
critical to the type of noise. Up to now I did not find any "real life
noise" that could be handled by the NB. I heard several comments that it
should work well with ignition type of noise sources. So I was very
surprised that I could not see any difference with or without the NB when
having troubles with the electric fence. So, you are not the only one having
doubts about this NB.

Evert, PA2KW

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Arie Kleingeld PA3A
Sent: Monday, September 25, 2006 20:52
To: elecraft at mailman.qth.net
Subject: [Elecraft] noiseblanker

Guys,

Still building #3612 bit by bit here.

1. Bare K2: no problem.
2. SSB module: disappointment as expected (very low output with my hc-4
element), replaced one resistor (easy mod), now much better.
3. Antenna tuner: Wow, excellent
4. BFO adjustments using Spectrogram: very good results, icing on the
cake (thanks Tom)
5. Built and installed the noiseblanker this weekend, but .... does it
work?

I tried to test the noisblanker (have an electric fence nearby). It does
not seem to blank noise. 
Measured several voltages on several transistors, controller and RF amp.
Nothing really strange except for the current to the agc input of the RF
AMP. I measured the voltage accross RP1 -3/4. With full signal (+40 over
9) 0,2V (connection 4 positive over 3) and with no signal minus 0,1 V (3
positive over 4).
What I would expect (checked the datasheet of the mc1350p) is voltages
of about 0,4V to 0,8V (0,1 mA to 0,2 mA through the 3k9 resistor). I
think the f AMP is faulty (?)

Can anybody verify these results?

Thanks in advance.

73
Arie PA3A


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