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

[Steve Harrison]

On 6/17/2024 9:25 AM, Jim W7RY wrote:
> I just watched his video...
>
> VERY POORLY done.   A true return loss of .31 dB, is anSWR of almost
> infinite. With approxamatly -14dB of return loss is 1.5:1 SWR.
>
> Cable loss has to be done with a short.

You mean Return loss, which is the reflected power from something.
Proper Return loss calibration requires a short, an open, and a
termination, regardless whether you use a Vector Network Analyzer or a
Scalar Network Analyzer. Through-loss is measured through the whole
string of connectors. Did anybody else notice the black, heatsink-finned
termination on the end of one of those connector strings??

Go back and watch the readout for "Min VSWR" when the Return loss is
showing -0.104 dB (with the N conns at 60 MHz): it shows a SWR of
167.277:1 at 60.7200 MHz  8-D I don't know what he was actually
measuring; but it certanly wasn't even Return loss, which should have
been no worse than around -20 dB with a decent termination, even through
a string of 20+ connectors.

> He never does say what the string of adapters is terminated with.
Doesn't matter: he wasn't measuring the right thing to begin with, let
alone with the right procedure. But I spied some sort of 5-watt-or-so
termination on the end of one of them.
> I'm not sure he knows how to run a VNA.

He also apparently doesn't understand the concepts and differences
between Return loss and Through loss.

Steve, K0XP