Hi Tony,
I am a cable design engineer and also a ham for 50+ years. I designed
Bury-Flex Tm, thank you for using it. It is an extremely popular coax used also
by NASA, Lockheed Martin, etc. What you are experiencing is most likely a
good dose of moisture in the coax cable, likely closer to the ant than the
xmtr, based on the time delay, but that is not certain (further depends in part
on how long the coax is in total. However, before we jump to that conclusion,
what you need to do is to insert a dummy load at every possible point (start at
Xmtr) and see when you start getting the same sort of VSWR heat up condition.
You may need to go right up to the connection on the ant, as the last point
that could show where the issue is (up to that point, from the last point
checked, as I'm sure you follow).
It is almost impossible that the Bury-Flex Tm is at fault because the blend
of PE that I use for the outer jacket resists even submersion in water or
various chemicals. The most obvious source for water ingress is at the
connectors or if an errant
cut has been made in the jacket. We have never had any problems with this
cable in the over 12 years since inception.
If you have any questions, or if I can help in any way, feel free. Yes,
winter is the worst time for these things !! HI
73, Steve, K1PEK
DAVIS RF Co., Div. of Orion Wire Co., Inc.
Wire, Cable, RF Connectors and wire aerial parts.
Rope, various blends cut to custom lengths
Cable assemblies, coax, audio, power, etc.
LMR, Heliax, Eupen
Commercial / Military
Custom Cable Design
tel: 978-369-1738 Please contact Steve Davis
www.DavisRF.com
>
>
>
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>
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 20 Dec 2011 22:11:53 -0800
> From: "Jim W7RY" <jimw7ry@gmail.com>
> Subject: Re: [TowerTalk] SWR Problem Balun or lightning protection?
> To: "Tony" <dxdx@optonline.net>, <towertalk@contesting.com>
> Message-ID: <2AE0C3F9FFFB46869B5FFD525C3EC347@Laptop>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Are you using the same wattmeter? Or are you using the meter in each radio?
>
> 73
> Jim W7RY
>
>
> --------------------------------------------------
> From: "Tony" <dxdx@optonline.net>
> Sent: Tuesday, December 20, 2011 9:12 PM
> To: <towertalk@contesting.com>
> Subject: Re: [TowerTalk] SWR Problem Balun or lightning protection?
>
>> All,
>>
>> I bypassed the lghtning protection and the SWR problem is still there. I
>> installed a new coax connector on the shack side of the coax as well.
>>
>> I still have to check the balun, balun leads and the coax-to-balun
>> connector. There's nothing else inline. The coax (Bury Flex) and balun
>> (3KW M2) were installed a few years ago.
>>
>> I just checked the system again with two different 100 watt rigs and
>> found that:
>>
>> - I can transmit for 2 or 3 minutes from a cold start before the SWR
>> starts to rise
>> - the SRW returns to normal 30 seconds after I stop transmitting
>> - it takes a lot less time for the SWR to rise after the 30 second rest
>> period
>>
>> I did replace the ground wires with copper strap a few months ago, but I
>> haven't made any other changes to the tower and antenna system.
>>
>> Why do these things always happen during the winter ; )
>>
>> Tony, K2MO
>>
>>
>>
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> ------------------------------
>
>
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