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Re: [RFI] advice wanted: finding the source of mixing products

To: rfi@contesting.com
Subject: Re: [RFI] advice wanted: finding the source of mixing products
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Mon, 24 Feb 2020 12:47:58 -0800
List-post: <mailto:rfi@contesting.com>
On 2/24/2020 11:25 AM, Matt NQ6N wrote:
I'd also welcome ideas for things to test/try that might shed some light on
what is going on.

Hi Matt,

Several suggestions. Ideally, this is a quest that requires help from another ham. One of you transmits while the other pokes around with that portable RX. Without that help, a good first move is to listen for the mix product(s) on a second radio while a directional antenna is rotated while transmitting, noting the direction(s) where the IM product(s) peak. With that information, transmit keydown and poke around with your portable RX.

As to the harmonics -- they are generated by the rectification. Even the most heroic stubs or bandpass filters in you station have zero affect on the IM process.

A great first move is to first search out and destroy (replace) ALL outboard SMPS that you can find, and put serious ferrite chokes on the AC cord of any built into equipment (appliances, home entertainment systems, anything plugs into the wall and has any form of electronic control). Search out and replace anything with variable-speed control of a motor (HVAC systems, etc.)

73, Jim K9YC
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