Carl, that's true, they do take a bit of time to fine tune, but once
tuned, you usually don't have to retune much.
So you may lose a QSO or two, but afterwards you can operate.
I have never used the MFJ so I cannot comment on it.
I can only say that I rarely saw my two units because the boys here in
the Bavarian Contest Club were always loaning them out for contest
expeditions.
73
Rick
Carl Moreschi wrote:
>I had an MFJ 1026 noise cancelor for a while. I found it quite effective at
>removing various noise sources but there were problems with it. I had an
>outside noise antenna for it. The noise antenna did not hear the noise as
>well as my normal antenna. So I typically had to reduce the signal from the
>normal antenna to match the strength from the noise antenna. Then I would
>have to adjust the phase to get the noise to cancel. This usually took
>about a minute to get everything adjusted properly and all the noise
>removed. At that point the signal I was trying to hear usually left and was
>gone! I sold my noise cancelor a few months ago.
>
>Carl Moreschi N4PY
>121 Little Bell Drive
>Bell Mountain
>Hays, NC 28635
>----- Original Message -----
>From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
>To: <tentec@contesting.com>
>Sent: Monday, January 29, 2007 4:56 PM
>Subject: Re: [TenTec] Orion 2 HW Noise Blanker
>
>
>
>
>>On Mon, 2007-01-29 at 16:26 -0500, joel hallas wrote:
>>
>>
>>>Jerry,
>>>
>>>That not quite what Toby's talking about.
>>>
>>>The old noise blankers used a noise sample in a wideband receiver to
>>>perform a short (not extended by selective filters) duration receive
>>>mute, much like current noise blankers operate except they pull a sample
>>>at the operating frequency from early in the receiver.
>>>
>>>The noise cancelers work in a different way. Instead of shutting off
>>>the receiver they have a phase and amplitude adjustment that allows the
>>>noise reduction signal to cancel the input from the regular antenna.
>>>This allows removal of even CW signals, or in band QRM if the directions
>>>are different. See Aug 06 QST, p 45 for more, if you like.
>>>
>>>73, Joel Hallas, W1ZR
>>>
>>>
>>>
>>Yah, I saw "noise xxxxxer" with separate antenna and thought noise
>>blanker with 40 MHz noise input.
>>
>>Noise cancelers at the antenna work on the noise antenna capturing full
>>strength noise but not much for signal which to me seems more than a
>>little serendipitous, especially with more than one noise source. Using
>>elevated directive antennas for both leads me to believe that the
>>"noise" antenna wouldn't get the noise the same strength as the main
>>antenna but would often acquire unwanted signals on the same frequency
>>from the direction the noise antenna was aimed. Might as well listen
>>with a vertical, "equally noisy in all direction." Seems to me the
>>directive antenna (admittedly its inconvenient to get directivity on 160
>>meters on a city lot with anything larger than a 2 meter diameter multi
>>turn loop) may be a better investment in S/N unless the noise source is
>>extremely local and then it might be most profitable to cure that noise
>>on the ham's own premises.
>>
>>I could envision three towers with identical beams all pointed the same
>>direct (that of the desired signal and some DSP processing with three
>>front ends to determine the direction of the unwanted and then to do
>>some directional enhancement, but I question whether it would do better
>>than just phasing the extra beams for better horizontal and vertical
>>directivity.
>>
>>E.g. I think the MFJ device (which they did NOT invent) will fail to
>>make an improvement more often that it makes an improvement. And one in
>>the receiver would do no better.
>>
>>--
>>73, Jerry, K0CQ,
>>All content copyright Dr. Gerald N. Johnson, electrical engineer
>>
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>>
>>
>
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>
>
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