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Re: [TowerTalk] Fw: Amphenol PL259

To: "David Branson KC0LL" <KC0LL@HOTMAIL.COM>, <TowerTalk@contesting.com>
Subject: Re: [TowerTalk] Fw: Amphenol PL259
From: "Steve Katz" <stevek@jmr.com>
Date: Tue, 5 May 2009 10:45:42 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

At work for over 26 years we put a small washer in the PL259 so the reducer 
mashes the shield tight between the body and reducer as it is screwed in. We 
never solder the shield. After all, even the center pin of the PL259 is only a 
pressure fit in the SO239. In 26 years and 1000's of mobile coaxes installed we 
never had a problem doing it this way. This is much more foolproof than 
soldering and heating (melting) the center insulation. Larsen antennas use to 
come with a Teflon washer in the PL259 bag! Teflon or plastic worked fine, but 
I have also used very small metal washers. 

::I've never had any problem soldering the braid through the solder holes, 
flowing solder through the braid and into the surface of the reducer.  It takes 
five seconds with the right soldering equipment and results in a very strong 
bond without overheating anything.  Keywords, "right soldering equipment."  :-)

As for RG213 or RG8, we ALWAYS fold the shield back over the outside jacket and 
screw the outer body of the PL239 over the shield, smashing the shield between 
the outer jacket and the body's threads, then cut the shield that sticks out 
with a knife held tight against the body and turn the body, it cuts it nice and 
flush. We (of course) solder the center pin. This has been 100% reliable and 
works better than soldering. Also, it is easer to get new guys to do it right 
100% of the time than the soldering/melting way. On antennas up in the air it 
holds the coax in the connector MUCH better than it hanging from only the 
shield, poorly soldered at best. I know you need a strain relief, but on 
mountain tops with ice you need all the help you can get.
Not wanting to start a debate, but this works, I know it works, and for us it 
works best.

::No debating.  But this introduces a larger impedance discontinuity than doing 
it the way the connector was designed to be used, where the cable's outer 
conductor continues up inside the connector body until it is within 1/16" or 
less of bottoming out against the dielectric material inside the connector.  On 
HF, it probably makes no difference one way or another.  At VHF, it makes quite 
a difference.  I routinely sweep UHF cable assemblies to 300 MHz, and with a 
1.2 GHz Termaline for a termination, get ~30 dB return loss at 300 MHz on most 
dual-UHF connector cable assemblies (short patch cables); using the "fold the 
shield back over the jacket" method described above, that drops to 10-12 dB at 
300 MHz.  Still  not "terrible," but not nearly as good as 30 dB.  The 
difference is obvious and repeatable.  For those of us using these connectors 
at 144 and 222 MHz, it's worth doing it the old fashioned way.

WB2WIK/6



  
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