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Re: [RFI] Power Line Noise in Indonesia

To: "Roger D Johnson" <n1rj@adelphia.net>,"Simon Martin" <simon@knaap.co.id>
Subject: Re: [RFI] Power Line Noise in Indonesia
From: "Tom Rauch" <w8ji@contesting.com>
Reply-to: Tom Rauch <w8ji@contesting.com>
Date: Tue, 20 Jul 2004 14:07:30 -0400
List-post: <mailto:rfi@contesting.com>
> >
> > It's an interesting design - I wonder if anybody you
know has built it
> > and how it worked.
> Unfortunately, no. It looks like it might help in
conjunction with
> a directive receiving antenna. I'm surprised that some
> manufacturer doesn't offer this (MFJ?).

I haven't looked at what you are talking about, but I expect
it is a tunable noise receiver that you place on a clear
frequency with only noise, and the receiver drives a blanker
for signals in the main receiver system.

If so, it cannot be a phased system or a noise subtraction
system. It has to be a blanker.

The problem is it would be a level threshold trigger for a
gate that turns of the receiver system. In effect this
punches a hole in the signal.

It is useful only for short sharp pulses like ignition,
ringing noises or multiple noises cannot blanked without
degrading desired signals. The noise duty cycle has to be
low, and peaks sharply defined.

I did suggest to MFJ that I would design one if they built
it, but it never happened. I did have just such a system in
my old diesel truck, to blank sharp pulses from the injector
solenoids. I'm not sue how it would work with power line

73 Tom

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