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Re: [TowerTalk] How lossy are PL-259s at HF?

To: "'towertalk'" <towertalk@contesting.com>
Subject: Re: [TowerTalk] How lossy are PL-259s at HF?
From: <charlie@thegallos.com>
Date: Tue, 18 Jun 2024 10:17:37 -0400
List-post: <mailto:towertalk@contesting.com>
Rob,
Totally agreed, and what eventually failed on that barrel connector
(disclaimer, it was probably 5-10 years old)

Now here is a good technical question - WHAT is the spec for min/max
diameter of the cup?  Rather than drag connectors (which is a good rough
way) - I can drag a set of pin gages in a go/no go handle.  I was just
wondering if you (or anyone on thread) knows?

73 de KG2V

Charlie


-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Rob Atkinson
Sent: Tuesday, June 18, 2024 9:16 AM
To: towertalk <towertalk@contesting.com>
Subject: Re: [TowerTalk] How lossy are PL-259s at HF?

I'd say when it comes to loss with UHF connectors the most critical thing is
the machining of the male pin and the female cup fingers.
Amphenol females are made so that you feel some resistance when you plug the
UHF male into the jack.  That grip on the center pin is important.  Poorly
made jacks that don't make good pin contact are where you have resistance
and loss, so much so that in cases of 1 KW continuous duty, the jack burns
up after several minutes.  A good jack will hold a PL259 body by the pin
hanging down with the threaded collar loose.  If the PL259 falls out,
something is wrong, either the male pin isn't the right size or the jack
isn't holding it tight enough.

When shopping for UHF connectors at a hamfest, bring an Amphenol male and
use it to test any connectors that have a UHF female involved.  Do not be
enticed by pretty looking jacks that are silver plated with what appear to
be teflon dielectric and gold plated pin cups.  In my experience these
off-shore jacks may fail to hold the male vertically and will heat up if
used.

73
Rob
K5UJ

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