[TowerTalk] Fwd: Fwd: sealing PL259's

[Roger (K8RI) on TT]

I would suggest, "Don't do it!" Whether the compound uses the acetic 
acid, or a non acetic curing agent, these are water proof. They are not 
moisture proof.  I've seen them used for years with no problems and I've 
seen them fail in less than a year.  Silicone greases are a much better 
choice. I worked for the company that developed these compounds and 
greases for many years.  (over 33 years by the time I retired)

If you can find it, DC-4, or DC-5 compounds (Silicone grease) is ideal 
for flooding connectors.  I'd stay away from anything that cures.  There 
is no need and it can make the connectors a Bit...ch to get apart.  Most 
any "non conductive" Silicone grease is great and should be available at 
most automotive stores. Just don't try to get tape to stick on anything 
with Silicones on the surface.Unlike hydrocarbon based greases, it's non 
conductive even if it breaks down.  (there is no carbon in it, When it 
breaks down you normally get SiO2 (Quartz powder, or chunks)

I once saw some commercial circuits potted in plastic cases.  It 
completely dissolved/corroded the runs on the PC boards.

NOTE DC-4 and 5 compounds were developed for use in WWII to keep the 
spark plugs in B17s and B24s from arcing over at altitude.

HOWEVER there are side effects to flooding connectors.  It allows for 
pressure changes between the inside and atmosphere with both temperature 
and atmospheric pressure changes.  This can cause the grease to flow, or 
moisture to "wick",  Even the aquarium seal is not moisture proof.  It 
uses the moisture in the air as a catalyst for curing.  It can allow 
moisture migration and condensation.

OTOH I've seen plain old UHF connectors, screwed on over the braid of 
RG-8 folded back, out in the weather with no waterproofing, or even tape 
and it had been out there for years!  I've seen the same type of 
connections covered with house paint.  They had been in use for decades 
(how many, I don't know, but the hams using them had no complaints.  How 
much of the power going into the coax was actually getting to the 
antenna and being radiated as desired? Who knows?  But again, like many 
hams using big, expensive, poor performing antennas, they made contacts 
as desired and were apparently satisfied.

As a new ham using a light bulb for a dummy load, I worked some DX.  
Surprised? Certainly. Satisfied? Certainly not!

Ideal band conditions made up for a less than ideal dummy load.

Filling the connector and then sealing it with tape should really slow 
the curing process.  <:-))


  73,

Roger (K8RI)



On 5/28/2015 3:25 PM, n8de at thepoint.net wrote:
> Before screwing the outer shell on the inner portion, flood the inside 
> of the connector with RTV silicone seal (non-acetic acid type - like 
> aquarium seal).
>
> THEN .. screw the outer shell tightly onto the inner portion .. and do 
> the 'double tape wrap' suggested by others.
>
> No water going to get into the connector/coax to do damage.
>
> 73
> Don
> N8DE
>
>
>
> Quoting Patrick Greenlee <patrick_g at windstream.net>:
>
>> A good wrap of electrical tape lasts pretty well and can be built up
>> pretty easy just in case you have tape  but not the right size of
>> shrink.
>>
>> Patrick   NJ5G.
>>
>> On 5/27/2015 10:08 AM, Doug Renwick wrote:
>>> Roger try putting some thick walled heat shrink over the jaws like 
>>> 3/4" and
>>> shrink it down.  Yes it needs to be replaced every so often but it sure
>>> protects the connector shell.
>>>
>>> Doug
>>>
>>> I wasn't born in Saskatchewan, but I got here as soon as I could.
>>>
>>> -----Original Message-----
>>>
>>> Use a thin sheet of  Silicone rubber in a "U" shape inside the 
>>> pliers to
>>> protect the connectors.  It works for me, but I'm often too 
>>> impatient to
>>> worry about a cheap PL-259 (Even Silver plated Amphenols are cheap)
>>> BNCs are basically miniature N connectors, bur they lose a lot to scale
>>> and are very weak.  I've never seen them used outdoors.  It tales 
>>> little
>>> strength to pull the coax out of one, making them an interconnect only
>>> for me.
>>>
>>>
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-- 

73

Roger (K8RI)


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