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Re: [RFI] Weird RFI Episode

To: rfi@contesting.com
Subject: Re: [RFI] Weird RFI Episode
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Mon, 25 Sep 2023 02:53:45 -0700
List-post: <mailto:rfi@contesting.com>
On 9/25/2023 2:10 AM, Jack Ference wrote:
You must always “Frank” all PL-259 connectors using a small wrench to complete 
the physical and electrical connection.

And Frank emphasizes, as do I, that all connectors, including barrels and adapters, must be first quality. For me, that means Amphenol 83-!SP for cable-mount males, and comparable adapters; in the case of adapters, stamped MIL-spec used/surplus parts that I buy at ham flea markets. I'm not familiar with qualifications of components in parts of the world other than North America.

While there may be decent parts by other vendors sold as OEM parts to mfrs, some of which have the capabilities to QC them, I have learned not to trust anything but Amphenol and MIL stuff. If it isn't that top-quality Amphenol or MIL, I consider it JUNK.

When getting back on the air in 2003, I built a parts stash of various adapters from hamfest vendors, including those who advertise in QST. Over 5-10 years, those parts caused me all sorts of grief. Tees and elbows had tiny wire springs rather than the solid centers of real adapters; I had one melt during a contest. Others generated intermittents that were a pain to troubleshoot. A three-way female tee, supplied by a mfr of a VHF antenna, fell apart mechanically!

And don't get me going on the glorified zip-cord sold for power and speakers, which has super-thick insulation but with copper that's much smaller than the advertised gauge. AND the zip cord is LOUSY for RFI; ALL power and audio cables should be TWISTED PAIR, which strongly resists RFI, HUM, and NOISE, while zip cord does NOT! Cables for ALL such installations should be twisted pair, including those when they carry PULSED DC for applications like solar systems, where the charge current PULSE-MODULATED DC rectangular waves; that content is DC plus a VERY strong broadband RF component. The same is true of what goes into and comes out of CD-AC inverters. BTW -- the ARRL book on alternative power is a train wreck about this stuff!

This reflector is about RFI, so I'm going into the weeds, which is where the bodies are buried!

73, Jim K9YC
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