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Re: [TowerTalk] LMR-240 Ultraflex

To: <towertalk@contesting.com>,<john.brewer@us.schneider-electric.com>
Subject: Re: [TowerTalk] LMR-240 Ultraflex
From: "Jim Lux" <jimlux@earthlink.net>
Date: Mon, 21 Feb 2005 14:51:30 -0800
List-post: <mailto:towertalk@contesting.com>
Ooops, that was the peak power limit...
The average power limit is much lower... Looking lower down on the data
sheet...at 30MHz, they give 1.49 kW average.  Applying the same 6dB margin
for mismatch, you're down to about 370W.

The conditions at the bottom of the graph show 40C jacket, 100C
innerconductor temp, VSWR 1.0:1, no bending, etc.

So, it sort of depends on what you mean by "high power patch cables"... I
wouldn't be comfortable running  a kilowatt through it with arbitrary loads
and having it snaked around.

Something to think about.. For very short cables with solid copper center
conductors, the thermal path may be shorter longitudinally through the
center conductor, where the thermal conductivity is high, as opposed to
through the dielectric and jacket, where the thermal conductivity is orders
of magnitude lower.

When you buy semirigid microwave coax for cryogenic applications, you get
stainless steel jacket and silver plated stainless steel center conductors,
for just this reason.


----- Original Message -----
From: <john.brewer@us.schneider-electric.com>
To: <towertalk@contesting.com>
Sent: Monday, February 21, 2005 5:39 AM
Subject: [TowerTalk] LMR-240 Ultraflex


> I'm noting the power carrying capability and wondering if anyone's had any
> experience with this coax ( LMR240 ultraflex).
>
> Seems like it would be ideal for high power patch cables, since it's much
> more easily bent than larger (RG8/213) cable.
>
> I need to replace a 150 foot run, as well, and this cable seems attractive
> both from a price/spec standpoint.
>
> Are there any gotchas in its use?
>
> John K5MO


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