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Re: [TowerTalk] ...and another coax adapter question

To: Scott Townley <scott@nx7u.net>, Jack Brindle <jackbrindle@me.com>
Subject: Re: [TowerTalk] ...and another coax adapter question
From: "Richard (Rick) Karlquist" <richard@karlquist.com>
Date: Sat, 25 Nov 2023 17:24:43 -0800
List-post: <mailto:towertalk@contesting.com>
You misunderstand what the definition of "insertion loss" (IL) is, as
used by RF component vendors. IL = incident power (input) - transferred power (output). The device under test (DUT) has both "mismatch loss",
where some of the incident power is reflected back to the source and
therefore is not transferred to the output; and dissipative loss,
where power is lost by being absorbed by heating the DUT.  So called
mismatch loss does not result in heating of the DUT.  Your
calculations are not valid.  Hope this makes sense.

73
Rick N6RK

On 11/25/2023 10:51 AM, Scott Townley wrote:
If that's the case, then wouldn't an insertion loss test reveal such an issue?

For example, I was deconstructing the power handling of a Charter Engineering B5-series coaxial relay (N-female connectors).  If I map "max insertion loss at x GHz" to the average power rating on their published chart, at every point the dissipated power comes out to 11 watts.  That tells me that "good" N-connectors can dissipate 5 watts, and for that mechanical form factor I should be able to derive a power limit based on measured insertion loss.

Or are the physics of power handling in "not-so-good" connectors different from what would be revealed by an insertion loss measurement? Assuming of course that we are not in the realm of high voltage breakdown of the dielectric (or maybe that's exactly the difference?).

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