[TowerTalk] PL259 Insertion Loss?

[Jim Lux]

More like..  Loss<  0.3 dB on the power meter in mfr test using 0dBm levels.  So as you point out mismatch contributes as does meter uncertainty, as does fixture effects. Basically it's a test that the connector isn't misassembled (missing center pin) or something like that.

On Jan 14, 2012, at 10:45, "Rick Karlquist" <richard at karlquist.com> wrote:

> 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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