[Elecraft] OT: SO-239 Connector Selection

[Edward R. Cole]

Since most of you are talking about HF, I suppose they are fine.

Professionally, I had the most quality control issues with 
PL-259's.  I quickly decided that only Amphenol brand were to be 
bought.  They had much better plating for soldering.  The problem 
usually came from the extra heat required to solder the shield.  Very 
easy to melt the insulation.  All our antenna were specified with 
N-connectors which have gaskets the provide some wx sealing.  Of 
course we double taped connections that would be outside.

Anything that requires good impedance match will do better with N, 
TNC, or 7/16 style connectors.

All my cables even down to 500-KHz use N-connector except where 
connection with a radio or commercial antenna come with UHF.

73, Ed - KL7UW
at 1296 up I often use sma connectors on low-power equipment.

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Message: 13
Date: Thu, 22 Jul 2010 17:54:43 -0000
From: "Ken Kopp" <k0pp at rfwave.net>
Subject: [Elecraft] OT: SO-239 Connector Selection
To: <elecraft at mailman.qth.net>
Message-ID: <ACDEF2099BE54AADB7632B69E498BEDD at shack>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
         reply-type=response


My experience with SO-239' / PL-259's -was- at
VHF and UHF, and I said so in my posting.

I was made aware of this when the Colorado Springs
radio club ordered a 4-port divider to feed their 2M
repeater's antennas and they specified / insisted on
me building it with SO-239's.  I shipped it and within
a few days they were complaining of high SWR.

Before getting the original one back I built and
shipped a second unit, only to get the same report.
It was only when I built the 3rd unit with N's did it work
correctly.

My friends at the NBS labs ... who originated NBS
yagi design (W0PW / W0EYE) ... along with the
particular power divider design ... explained
what was going on.  The non-50 ohm SO-239's
connected to the 35 ohm transmission line / power
divider were influencing the impedance of divider.

My years at CU's radio astronomy lab and the NBS
cafeteria represent some of the best "learning" in
my career.  I learned much via napkin tutoring done
by some of the nation's best "radio" minds.

73! Ken Kopp - K0PP



73, Ed - KL7UW, WD2XSH/45
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