On 11/11/2013 7:46 AM, Dr. David Kirkby wrote:
On 11 November 2013 08:04, Roger (K8RI) <k8ri@rogerhalstead.com> wrote:
With a center fed, sloping dipole, which is far from being a balanced
antenna, I have blown Male and the double female connectors by moving 50 to
100 KHz off resonance. I've also had nearby lightening strikes take them
out.
I had several double female Amphenols short out, used for splicing in
rotator loops and smaller coax feed to the sloping dipoles. They still
looked like new and I wanted to keep them for examples, so they now have
a band of red tape around the middle. They look OK and an OM meter shows
them to be OK, but they won't work even with a 100W on 75 or 40.
The red tape is because the inevitable happened and one found its way
back into the system.
I forgot to mention the part about being easy to assemble, but fussy
about dimensions.
Another problem with N type and non captive pins is the coax center
conductor migration. This is a problem in vertical runs and feeds to
sloping dipoles that swing in the wind.
With vertical runs the linear migration can normally be solved with
LMR-400 and 600 by making a 1 or 2 turn coil just before the connector
(top and bottom). As long as the radius is not too tight, I've never had
it migrate in turns
73
Roger (K8RI)
I suspect part of the problem is that they are often not assembled
properly. Often the male or female are too far forward or too far
back, which gives a less than optimal electrical contacts, and I
suspect thermal contact too.
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