Barry, try it with the end shorted and use the SWR/graph version of the
test. Either way, 20 ft is probably too short to get a good test. We use
it a lot here on incoming inspections, and the thing correlates very well
with lab results.
As for the coax, it has a nominal life expectancy of 5 to 10 years, on
the shelp or on the pole, so your results could very well be right.
Press Jones, N8UG, The Wireman, Inc., Landrum, SC, 29356
Sales(800)727-WIRE(9473) or email@example.com.
Tech help (864)895-4195 or firstname.lastname@example.org
Our 21st year!
On Wed, 1 Jul 1998 16:59:40 +0000 "Barry Kutner" <email@example.com> writes:
>Hi all - I am in the process of doing some station layout changes and
>some recabling in the process. Just for the heck of it, I pulled
>an old (maybe 20 years?) 20 ft length of a no-name, foam dielectric
>RG8/U jumper that went between my Top Ten relay box and wattmeter, and
>put it on my Autek RF-1 to check for losses.
>Following Autek's instructions, I tuned for minimum Z. At 28 Mhz,
>according to their formula, my loss was 1.3 db and at 7 Mhz it was 0.7
>db! I used the formula 0.17 x Z = loss in db (for 50 ohm coax). This
>seems awfully high, or does it?
>It is old coax, but only 20 ft long. Does it really deteriorate like
>that being indoors the whole time? Or is that formula not correct?
>Barry Kutner, W2UP Internet: firstname.lastname@example.org
>Newtown, PA Frankford Radio Club
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