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Re: [Amps] UHF Connectors

To: amps@contesting.com
Subject: Re: [Amps] UHF Connectors
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Tue, 12 Nov 2013 01:59:10 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
On 11/11/2013 2:02 PM, Jim Brown wrote:
On 11/11/2013 10:37 AM, Fuqua, Bill L wrote:
Isn't "UHF Connector" an oxymoron?



The name dates from the '30s or early '40s.  No question that there's a
small discontinuity due to the Zo of the connector, but it certainly
doesn't matter below 50 MHz, and at higher frequencies is often swamped
by line loss.


I have on average 10 connectors in line from the amp to the antennas. 228 feet. With UHF type the additive loss is so small as measured on the VNA it's insignificant through 10 meters and only a slightky bit more on 50 MHZ I haven't checked 2-meters.

As the arrays for 144 and 440 are not going back up and the only VHF/UHF antennas will be Diamond duoband verticals Loss isn't much of a concern. I leave the VNAs connected through a Delta-2 switch, so every tune up van have the characteristic traces overlain to see any differences. The sensitivity is good enough to see the effects of the wind on the antennas and trees.

After using a 4170C for about a year I added a second one to the second station. They sure are different than the old MFJ.

73

Roger (K8RI)


Several years ago, I made up a dozen or so lengths of coax for a DX trip
using very low loss cable that I'd bought at a great price, surplus from
a telecom bankruptcy -- construction much like LMR400, except #10 solid
copper for the center, excellent braid/foil shield.  As a test, when I
was finished, I connected them all in series, about 1,200 ft, and
measured with HP generator and HP spectrum analyzer up to about 500 MHz.
I had about 23 83-1SPs and 11 or 12 barrels in line. The loss at 500 MHz
was less than the published spec for the cable. Loss was measured by
substitution (that is, differencing a short direct connection between
generator analyzer with the cable under test) at all of the test
frequencies.

73, Jim K9YC
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