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Re: [RFI] Power Line Noise in Indonesia

To: Tom Rauch <w8ji@contesting.com>,"Roger D Johnson" <n1rj@adelphia.net>,"Simon Martin" <simon@knaap.co.id>
Subject: Re: [RFI] Power Line Noise in Indonesia
From: Pete Smith <n4zr@contesting.com>
Date: Tue, 20 Jul 2004 14:14:19 -0400
List-post: <mailto:rfi@contesting.com>
At 02:07 PM 7/20/2004, Tom Rauch wrote:
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

As I recall, this is what Collins offered at one point as an add-on for the KWM2A -- it attached to the underside of the hatch in the cabinet and, from memory, operated at ~46 MHz. We had one of these radios in the old State Department club station next to the elevator motors of a 9-story building in downtown DC. I don't recall that the blanker was particularly effective on most of the urban noise environment.

73, Pete N4ZR
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