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Re: Topband: Elimination of Treadmill RFI on 160 meters

To: topband@contesting.com
Subject: Re: Topband: Elimination of Treadmill RFI on 160 meters
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Thu, 29 Jan 2015 12:48:07 -0800
List-post: <topband@contesting.com">mailto:topband@contesting.com>
On Thu,1/29/2015 11:18 AM, Tim Shoppa wrote:
A deep "4 inch box"? Add extension rings if necessary? Ganged outlet boxes?

Slide #6 in http://nccc.cc/pdf/CQP-RFI2013-2.pdf shows how I mounted a 20A line filter in deep multi-gang boxes. Each box is sized to hold a single duplex outlet or switch. I've forgotten the correct name for them, but they're in the big box stores, about $2 per section. All it takes to gang them is remove one side cover of the end boxes and both side covers of the interior boxes and screw them back together. I bought these at Home Depot. I later found a cover for the rest of the box -- some of the less common stuff like multi-gang covers I had to buy online from amazon, etc.

Another good way to do it is to buy a suitable length of ordinary extension cord (same big box store), break it close to the male plug connect the two ends to the line filter, going in and out of the box with compression fittings, and winding a common mode choke on the longer output side of the cable. I've done that with a cable where the output went to a multi-output strip or 3-way split.

When you're wiring to the filter (and outlets) ALL THREE WIRES MUST be connected on both sides.

Here's a link to ARRL's page about grow lights.

http://www.arrl.org/grow-light-rfi

It includes a link to line filters that W0IVJ and W0QE have developed. From the spectrum sweeps, it's not clear to me that their filter goes down below 40M.

73, Jim K9YC
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