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Re: [TowerTalk] PL259 Insertion Loss?

To: "Tony" <>
Subject: Re: [TowerTalk] PL259 Insertion Loss?
From: "Rick Karlquist" <>
Date: Sat, 14 Jan 2012 10:45:09 -0800
List-post: <">>
Tony wrote:
> All,
> I've always assumed that UHF connectors had negligible insertion loss
> below 30MHz, but I recently spotted a couple of quotes on the web that
> put losses between 0.3 and 0.5db @ 30Mhz. If that were the case, the
> cumulative effect of a typical installation with 6 to 8 connectors would
> not be so negligible, especially on 10 and 12 meters.

There is a semantic misunderstanding here about the meaning of
"insertion loss".  Everyone on this reflector seems to think
it refers to dissipation loss.  It doesn't, as commonly used by
connector vendors.  Instead it refers to what is more precisely
called "transducer loss" or S21 in terms of S parameters.  In
a PL259 at 30 MHz, the transducer loss is almost all in the form
of "mismatch loss", which is a theoretical number and does not
produce any physical heat.  Thus 0.3 dB insertion loss basically
means 0.3 dB mismatch loss, or something like 6% reflected power.
Even that number is seriously sandbagged IMHO, because nothing
of the size of a PL259 at 30 MHz could account for that much mismatch,
no matter how stupidly made.

Rick N6RK


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