RadioBanter - View Single Post - [FOAR] Coax Loss vs Connector Loss

Ralph Mowery

In article , rec-radio-info-
says...

Of course after I mentioned this out loud the questions started. Why didn't
he test this at a usable frequency, something like 145 MHz, or in the GHz
band? Then there were those who said that this wasn't a real test and that
it should be tested with coax in between the connectors.

I discussed this all at some length and one idea we had was that perhaps
the intersection between the coax and the connector was the problem, that
each transition between coax and connector and back was introducing the
loss.

I wondered if there was a way to test this.

Turns out that somebody already did. Back in July 2015 Jim K9YC decided
that this needed to be tested. That's right, another Jim.

He set up a test with a dozen 100 foot lengths of low loss coax, that's
just over 365m of coax. This included two dozen PL259 connectors and 11
barrel connectors. He tested using a calibrated HP generator/voltmeter rig.
The total loss was and I quote: "one dB or so less than the loss specified
for the cable by the manufacturer". So, the run with connectors was
actually better than a single run of coax.

Connector test have been ran by many over the years. One way to weed
out the connectors is to put about 1 kw of power through them to a dummy
load and feel for heat after around 30 to 60 seconds.

While the coax connectors made it ok, I melted out an inexpensive 2
position antenna switch and their cheep connectors and the loose way
they were connected to the body of the switch. The antenna had a high
swr and I was using a tuner between the amp and the switch.

There was another quality switch before the inexpensive one and it took
the power just fine. It did not even get warm while the other was
melting out.