[OKDXA] Coax Replacement

[KD5DLL]

Nelson PLEASE give Doug Xander my best and thanks for the info.
----- Original Message -----
From: "Nelson Derks" <ac5up@vei.net>
To: <okdxa@mailman.qth.net>
Sent: Monday, September 16, 2002 9:48 PM
Subject: Re: [OKDXA] Coax Replacement


> > Ok I have heard who like what type of coax but why did you select the
coax
> > that you are using. PLEASE edumacate me.....
>
> Ohhhh... Like we've never heard THAT before from The 'DLL...
>
> By commercial standards, the original RG-8 coax was designed as a low-cost
> 50 ohm feed line in non-critical applications at moderate power levels. It
> uses a durable solid polyethylene dielectric with a service life in the
five
> year range (really, look it up!). RG-213 is the mil-spec version with a
> non-contaminating PVC jacket that extends the service life closer to 10
> years. Old coax tends to go 'gooey' inside and will develop cracks in the
> sheath causing water migration problems and loss of efficiency. RG-213 is
> preferred, but there are cables sold as 'RG-213 TYPE' which isn't much
> better than RG-8 in terms of durability.
>
> In most cases, the selection is based on cost and usage. RG-213 is good
> through 10 Meters for moderate run lengths and shorter runs up to 50 MHz.
At
> 2 Meters and up, the loss characteristics become a factor and a foam coax
> like Belden 8214 becomes attractive... But, even a good foam coax like
> Belden has shortcomings in durability, heat resistance and impedance
> accuracy. 8214 doesn't like hot attics or sharp bends and isn't the first
> choice for phasing harnesses or tuned stubs, but, in a careful
installation
> it works well. Some Hams will sacrifice a few dB for the greater service
> life of RG-213 over 8214, but, for a little more money, you can have it
> all...
>
> Check out the specs at: http://www.timesmicrowave.com/products/commercial/
> for the LMR series from Times Microwave. These cables use a high silicone
> content outer sheath that's extremely abrasion resistant (compared to
> RG-213) and a high-density foam that approaches the crush resistance and
> impedance consistency of a solid dielectric cable, while maintaining
> superior loss characteristics. It's damn good coax and something you can
> install once and pretty much forget about for many years. Everything I do
on
> 2 Meters and up is wired with an LMR cable and I've had very good luck
with
> my VHF efforts. Part of that is due to the clean horizon on the slight
ridge
> at my QTH, but I do believe some credit must be given to the coax. I have
> two runs that have been up five years and the outer sheath still looks
new.
>
> As for the model numbers, they come from the outside diameter of the
cable.
> LMR-195 is .195" like RG-58, LMR-240 is a quarter inch cable like RG-8X,
and
> LMR-400 is the equivalent of .405" RG-8 style cables. LMR-600 and up
require
> custom connectors, but offer even lower loss characteristics approaching
> rigid Heliax style cables at a fraction of the cost. Visit the web page,
> it's worth the time...
>
> Also, rumor has it Doug Xander uses nothing less than LMR-800 and enjoys
> superior results... I suspect you would too, if your QRP rig was running
10
> gallons and had a Continental Electronics logo on the front panel, but
> that's another story.
>
> - AC5UP
>
>
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