[TowerTalk] A new thread on connectors 8^)

[Zivney, Terry]

A  new thread on connectors 8^)

I was investigating inexpensive connectors for LMR-600 (to run up the tower
to the different beams).  The genuine Times connectors were not considered
initially because of the high cost of UHF connectors.  I wanted female UHF
connectors so I could put male PL259s on the short flexible jumper cables to 
the stackmatch and antenna baluns.

It seems that the crimpon tool needed for LMR600 is different and more
expensive that the tools I have used for RG213, LMR-400, and RG8X. So,
I ordered a pair of UHF female clamp-on connectors from W5SWL. (This is
not a knock on his products).  The connectors arrived, sure looked great.
But, before I put the connector on the sample RFC-600 coax, I tried 
it with a PL259 cable in the shack. To my dismay, I could not  get the
two connectors to mate!

I tried several different makes and vintages of PL259 connectors. THe
genuine Amphenol solder-on PL259 went on only with the greatest difficulty.
Some of the silver-plated teflon hamfest connectors would not engage at
all.  The no-name crimp-on PL259s with the crimp center pins all worked great!

Scratching my head, I grabbed a genuine Amphenol Tee.  The male part went into
the W5SWL with no problem.  All of the different types of PL259s mated with 
the female parts of the Amphenol Tee with no difficulty.  The PL259s all
worked with the genuine Amphenol SO239, too.

Looking at the W5SWL female UHF connector, and  comparing it to the 
Amphenol females, I noted PART of the problem.  The W5SWL connector,
like many other UHF female  connectors, including cheap barrel  connectors,
starts the thread quite a distance from the end of the connector. Careful
examination of the various male connectors showed the same thing. The cheap
crimp-ons that worked with every female connector in the house have threads
almost to the very beginning of the shell.  The genuine Amphenol PL259
starts the thread farther back.  The hamfest specials start the thread
very far  back.

The problem is the combination of "missing threads" on the W5SWL female
and the various males ment that there was no overlap of the  threads to
screw the shell on.

A trip to the Amphenol website to look at the specification drawings
shows NO spec for where the  threading starts, just calling out the
thread size.  This is true for both the PL259 and the SO239.

This was the AHA! moment.

I purchased an Ameritron ALs-1306 this spring to help with the DXing.
I was unable to screw my existing jumper cables which had worked for
years with the  Titan onto the Ameritron.  The Ameritron amp uses
some UHF connector which is NOT an SO239, but appears to be a 
bulkhead  connector of some sort with threads looking very much
like those on the W5SWL connector that started this investigation. 

BTW, all of the shells of the PL259s screw onto all of the female
UHFs IF the center part of the connector (the part holding the male
pin) is left off.  So, the threading size is correct, just not the
threading position.

Also, a look at phtotographs of connectors on various web sites
suggests this problem could happen with N connectors as well, since
the threading appears to be variable on them as well (the thread
size is the same, and no spec is shown for the length of thread nor
the starting position).

I'm still looking for reliable information on female UHF connectors
for LMR-600.

Terry N4TZ