[TowerTalk] Fw: Amphenol PL259

Tue May 5 11:49:54 PDT 2009

Yes, I understand your point. Also, just wondering were you work? As to your application verses mine. At work we need a good, fast, and yet 100% foolproof way to do them. But, I don't agree you would get an impedance discontinuity with my way of installing them. At least when I sweep some of the cables I make for combiners I have not seen it being any different, the ID/OD ratio is basically the same either way. If you can keep from it, you don't use PL's on UHF anyway, . 
At work we are using "DS" RG58 coax using center foam dielectric, not solid dielectric, (ours are mostly used on 800 MHz) and foam is very easy to melt when you are upside down in a Taxi cab. Some of our government installs are specked-out on exactly how to do theirs.

At work we use "N" connectors on our RG213, 9913, 400 etc. 99% of the time, all our base antennas have "N". And we use crimp connectors most of the time with "N" or 7/16 DIN. 

The main problem we have had with connectors put on by others people for cement trucks, etc. is when they are wooled around a lot, over years copper ends can break off and short them out. With the shield folded over the out side of 213 this is an non issue. On anything that an impedanance discontinuity would matter, like 800 radios we would be using "N". On our 2.4 or 5.8 microwaves, we would of course be using hard-line or at least supperflex, and above that wave guide, so this would be a non issue to us.
You NEVER use a PL259 on UHF if you are worried about impedanance discontinuities. These are only good for HF and not great at VHF. But, we are forced to use them when the radio has them on the back. Have you ever swept them on UHF or 800? They are horrible when you get to 800 no mater how you install them. I use "N" or 7/16 DIN when ever possible for all my ham radios, and 7/8 for all coax I use www.kc0ll.net. But, the bottle neck is the back of the radios.
Anyhow, that is my input, I am sure I have bored everyone at this point. 
End of discussion..

David F. Branson

Senior Technician
Action Communications, Inc. 
Tucson, AZ 
520.792.0326
520.792.2709 fax
KC0LL at comcast.net
www.kc0ll.net
www.ActionCommunications.com

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  ----- Original Message ----- 
  From: Steve Katz 
  To: David Branson KC0LL ; TowerTalk at contesting.com 
  Sent: Tuesday, May 05, 2009 10:45 AM
  Subject: Re: [TowerTalk] Fw: Amphenol PL259

  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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