[UK-CONTEST] Coaxial Connectors

[David]

I suspect the limit on a PL259/SO238 combination with PTFE insulation is
when the coax dielectric melts.  PE has a lot lower thermal limit than PTFE.

Similar would apply to the N type plug/socket.

The skin effect would cause more connector heating for the same power as
frequency increases.

However unless you have a three phase power supply and a large rack sized
linear I doubt if either connector type would be a limiting factor on HF. If
you are worried could go to LDF5-50 and DIN connectors...

But for real power the local MW TX site runs TXs at 1600Kw PEP. Probably
plumb the feeder in to the TX with no connectors.

73 David
-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Chris Tran GM3WOJ
Sent: 04 February 2012 13:40
To: uk-contest at contesting.com
Subject: Re: [UK-CONTEST] Coaxial Connectors

Hello all

I've been driven inside by heavy rain, so here is my 50p worth about coax
connectors...

There are different qualities of 'pressure seal' PL259 plugs - some poorer
quality ones have thin metal for the threaded ring that tightens onto the
socket and if you over-tighten them they fall apart - the threaded ring
separates from the body of the plug.

Despite the official power rating of N-types being 5kW, some well-respected
websites indicate that, from experience, they should not be used above 1kW -
the centre pin is inadequate. Assuming 50 ohms, 400W = 2.8A, 1500W = 5.5A,
10kW = 14.1A

I remember BBC antenna expert Mark GM4ISM telling me years ago that, if
correctly fitted and terminated, a PL259 was good for 10kW.   (intermittent
service I assume!)

73
Chris
GM3WOJ

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