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Re: [TowerTalk] Coax Cable choices

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Coax Cable choices
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Fri, 18 Aug 2017 12:05:26 -0700
List-post: <mailto:towertalk@contesting.com>
On 8/18/2017 11:16 AM, Richard Smith wrote:
I realize this question may be too generic, but what might folks here on 
Towertalk recommend for these applications?

Hi Rich,

About 10 years ago, a colleague acquired a lot of spools of virgin Commscope 3227, which is designed and specified for use at UHF in a wireless telecom application. He also acquired 2427K, which is the plenum version. It's solid #10 copper center with shield construction similar to LMR400. The loss spec STARTS at 500 MHz. :) It's a VERY robust cable, and has published loss characteristics comparable to the published specs for LMR400. About five years ago, I made up about 1,500 ft of cables for a DXpedition, and, using an HP generator and HP spectrum analzyer (as an RF voltmeter), found that 1300 ft of those cables (typically 100-200 ft long with Amphenol 83-1SP connectors) spliced using Amphenol barrels, measured BETTER than the published spec at 500 MHz!

Other than hard line and RG11 to feed my high dipoles, that's most of what's in my station, but I eventually ran out (or have been running low). I also found a NOS spool of Belden 8213 (RG11) at HSC that was about 85% full, and used it on the high dipoles.

A few years ago, when I needed more RG11, I bought Davis RF's RG11, which I subsequently measured and found loss characteristics equivalent to the 8213. And when I wanted to replace a collection of randomly acquired jumpers (from N6RZ's estate) to clean up crosstalk problems, I bought a spool of BuryFlex. I'm quite happy with those cables, and recommend them. I find them to be a very good alternative to Belden, which I consider the gold standard, but which carry excessive markups due to their distribution system through traditional industrial supply houses. I've seen no QC issues with Davis, the cables seem quite well made, they have been very good to deal with, and their prices are competitive. Part of my testing includes a high resolution TDR of the entire spool, as well as measurements of a shorter length to feed to Zplots to compute and plot VF and attenuation vs frequency.

Those are the only two Davis cables I've used, but I'd expect their other cables to be of comparable quality.

73, Jim K9YC


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