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Re: [TowerTalk] DIN to coax connector?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] DIN to coax connector?
From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
Date: Wed, 7 Sep 2016 00:00:44 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
The installation video agrees with you.

PL259s: The problem with solder type PL259s is usually not the braid that so many complain about, but rather the center pin. Most apply heat to the pin. This often results in solder getting on the outside of the center pin. There is little room in the female SO239 for the now oversize center pin. This causes the expansion of the receptacle to the point where future PL259s with no excess solder do not make a good connection. Extend the center conductor through the center pin far enough that the heat can be applied to it and the tip of the center pin of the PL259. The copper center conductor will carry the heat and thus the solder down into that center pin of the PL259. Solder will generally tend to flow toward the heat source. Heating the center pin usually does not heat the center conductor until the solder connects both. So heating the copper wire and the tip of the center pin "usually" causes the solder to flow to where you want it.

This mismatch can be difficult for the average ham to find as the connection may be intermittent and is often not visually evident leading to trouble shooting the antenna and or tuner.

The ARRL Hand Book has a pictorial of how to properly install PL259s, but there seem to be lots of variations out in the wild. If the braid isn't installed as per the directions, it can create a much larger impedance bump if installed on the outside of the PL259. You now have the entire length of threaded portion serving as an over size shield rather than the short gap between the end of the braid and the shell. making the area that is no longer 50 ohms many times that of a properly assembled PL259. It's handy on FD, or a temporary installation to just screw the connector over the braid rather than solder the braid in the connector basically creating a permanent connection. This "usually" works, but I've lost count of how many I've found in permanent installations, usually when there's a foot of snow on the ground.

I know that many of us need to save our pennies, but saving a few cents on a connector, while ruining many feet of coax is costing rather than saving. "Most" coax runs only have a couple of connectors, so they are by far the cheapest part of the installation. Here, using "good" connectors and taking the time "Properly" installed them will likely give better performance while saving money in the long run..

As many have said, the loss from the connectors does add up. Properly installed PL259s, crude as they are have very little loss. One improperly installed connector can have the loss and impedance bump equivalent to quite a few properly installed connectors. Add to that what damage they may cause to the coax over time along with degraded performance. The SWR improving with time is not a good indication of things getting better with age!

Today's top end coax cables often have a foil shield with fine Al wire for a braid. Water can cause that foil and braid to completely disintegrate in just a few months or less. True, much of that was done to save money, but the foil gives good coverage and the coax is lighter than one made using copper.

There is the approach touted by many, including me at one time, that water will be no problem if you properly weatherproof the connections. It only takes one lightning strike to remove the best of weatherproofing.

One strike to the top of my 100' 45G removed all of the weatherproofing and silver plating from the connectors "up there" and within 15 minutes My 200' 9913 hose had water running out of my rig onto the desk top.

73

Roger (K8RI)


On 9/6/2016 Tuesday 9:51 AM, Kelly Taylor wrote:
Far be it for me to argue with someone in the industry, but…

The DIN install videos I’ve seen suggest the centre conductor is soldered into a 
shallow well inside the connector, almost the way a conductor would be soldered to the well 
inside a chassis-mount SO-239. Considering the centre conductor of a PL-259 passes through to 
the end of the connector and is soldered there, with perhaps a greater degree of 
conductor-solder-connector contact to grip the conductor, and given the crimp-and-solder 
style PL-259s employ a similar clamping scheme to DINs, I’m just curious about the 
statement regarding mechanical superiority.

It seems the centre conductor might be the weak link. Can you clarify, Steve?

As for the crimp-crimp style PL-259s, is there a valid reason the instrux 
typically warn against soldering the centre conductor?

73, kelly, ve4xt,



On Sep 4, 2016, at 10:33 AM, Steve Maki <lists@oakcom.org> wrote:

On 9/2/2016 0:33 AM, Jim Brown wrote:

I've been gradually converting to all DINs everywhere that it's
reasonabl
Why? Are all your systems at UHF?
No. In my business we use nothing but 7-16 DIN nowadays and it does not take 
long working with them (like 5 minutes) to realize how superior they are, even 
if just mechanically (at HF). And of course I have a good supply on hand, being 
in the biz.

So when I ran all new hardline out to the towers a few years ago, it was an 
easy decision to switch to DINs on the main lines and on jumpers - at each end 
of the hardlines - to the point where I encounter a device with a UHF connector 
that is inconvenient to replace, like a wattmeter, balun, etc.

-Steve K8LX



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--

73

Roger (K8RI)


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