[Elecraft] OT trying to identify "mystery" coax cable

[WILLIS COOKE]

I don't know what kind of cable it is Lew, but the lower capacity per foot 
should make it better for VHF and lower the loss a bit.  You might put your watt 
meter at the dummy load end and measure the power out at 6 meters.  If it is 9 
or 10 watts, you have a good feed line so go for it, you have a bargain.
 Willis 'Cookie' Cooke 
K5EWJ 




________________________________
From: Lew Phelps K6LMP <k6lmp at me.com>
To: Elecraft Reflector <elecraft at mailman.qth.net>
Sent: Wed, April 13, 2011 11:58:51 AM
Subject: [Elecraft] OT trying to identify "mystery" coax cable

I was browsing through the local Salvation Army Thrift Store (where I sometimes 
go looking for low-priced antique treasures), and stumbled across a 50-foot 
length of RG-8-type coax cable. At the asking price of $6.00, I couldn't pass it 
up.

It has Amphenol male "UHF" connectors. And absolutely NO markings on the cable 
itself indicating manufacturer or type. The OD of the cable varies from point to 
point, but averages about .405 inch, which puts it in the RG-8b family. It is 
quite flexible, and clearly stranded center conductor, not solid.  Capacitance 
of the 50 foot cable was measured 1155 pF, or 23.1 pF per foot, which eliminates 
some RG-8 flavors that have 30 pF per foot.  The only distinguishing feature of 
the cable is that there appears to be a wire would spiral-wise (1/2 turn per 
inch) outside the standard foil shield and under the exterior rubber sheath.  
I've never need that construction before on any RG-8 cable.  (I haven't cut it 
open to verify the construction, because I don't want to have to de-solder and 
reconnect the Amphenol connector.) 


I attached the cable to my dummy load and to the HF output of my K3.  Keying the 
transmitter at 12 watts produces an SWR of 1.05:1 (external SWR meter) on all 
bands up to 6 meters, and continuity checks confirm that the cable has neither 
short circuit between shield and cable nor open circuit.  In other words, it 
appears fit for duty.

Two questions;
1. Anything else I can or should do to check the cable and make sure it's OK to 
use?  (Unfortunately, I do not own or have access to an antenna analyzer.)  

2.  Based on the "spiral winding" between the shield and outer coverk does 
anyone have an idea what specific cable this might be?

Thanks, and 73

Lew K6LMP


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