Fred Hopengarten wrote:
>On Fri, 11 Oct 1996 10:18:54 -0700 rattmann@cts.com (rattmann) writes:
>
>>Interesting things happen to connectors with aging. Last year I had a
>>piece
>>of RG-213 look "open" and it was driving me crazy finding the problem.
>> I
>>had a cable splice in a termination box, joining a cable-end male-N to
>>a
>>cable-end female-N. There was no strain on this splice. It turned out
>>that
>>over time (with lots of hot weather in San Diego), the center
>>dielectric of
>>the cable had migrated (pulled back) relative to the connector body.
>>The
>>male-N pin thus had retracted about 3/16 inch, and separated from the
>>female
>>pin, even though the male pin at one time had been in the right
>>position.
>
>
>K1VR: Curious. I discovered the same problem last winter here. When
>things got REALLY cold last February, my 40 meter beam stopped working.
>The problem turned out to be that an N connector splice in the K1XX
>asynchronous transformer (to feed a 50 ohm beam with 75 ohm hardline) had
>experienced this "n-connector pullback". The inner body of the N
>connector, on the female side, had retracted and was no longer making
>contact. Instead of attributing it to warm weather, as Glen K6NA does, I
>had attributed it to cold weather. However, at that time, someone wrote
>me that he had discovered the same problem in several places with N
>connectors on RG-213 at KN8Z, where the N connectors were taped
>vertically to a tower leg (as was true in my case). So it may be an N
>connector problem, not a weather problem.
Two questions:
Was the RG213 inner stretched before the connector was installed, or
maybe was the outer compressed? Over time, it would remember its
original configuration and the inner would pull back. Alternatively, was
the cable being stretched by its own hanging weight?
The second question is whether the N connectors were the original
design, or the modified ones with the captive pin and pressure sleeve?
It's very easy to assemble to original design so that it's only just
making contact, and the connector itself does nothing to prevent long-
term 'creep' of the inner conductor. The modified design is much more
resistant to these problems - I've given up using the old type
completely.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
Professionally:
IFW Technical Services Clear technical English - world-wide.
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