[TowerTalk] DIN to coax connector?

Wed Sep 7 00:00:44 EDT 2016

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 at 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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