[TowerTalk] Sealing coax connectors

[Bob K6UJ]

Thanks for the info Jim,  
now I understand the use of the Dow DC 4/5 more clearly.
I will have bullet proof connections now !

73,
Bob
K6UJ



On Jan 17, 2012, at 6:37 PM, Jim Thomson wrote:

> Dow corning DC4/5 is silicone GREASE !   It's  NOT RTV glop.     The  dc4/5 
> is formulated for electrical connections.
> The dc4/5   goes on the threads, the center pin.....and the mating female, 
> that the pin goes into.  It's displaces moisture,
> and  stops  microscopic arcing inside the connectors, where you have tiny 
> microscopic air gaps between the pin + female.
> Dc4/5 is typ 450-550 volts  per mil [ .001"]   Some of dow's tech notes list 
> it as 1 kv per mil.   If the pin bears down hard
> on the sidewall of the female, it makes contact. On the other side, where  a 
> tiny air gap results, the  dc4/5 fills the void.
> if the pin shifts about, the dc4/5  simply moves about as well, always 
> filling the voids.   All the telco's  use it on 7-16
> din connectors.   Andrew  supplies it in a small container with their 
> connector's.   Ken Hirshberg, at Cal-AV  labs suggested
> I use the dc4/5  on the 7-16 dins on his  baluns.  [ EB-3 variety].    You 
> only apply a thin layer of it.  It's  good form -56 C
> to well over 200 deg C.   OK, once the dc4/5 is applied, and connector 
> cranked tight, then use your favourite water proofing
> method.  BTW,  you can apply five times as much torque on any 7-16 din 
> connector  vs  any Type N connector.  The 7-16
> Din comes with the silicone rubber O ring.  The inner spring collet [female] 
> is the  RF braid connection..and not the outer shell.
> The inner spring collet + outer shell are  zero ohms between em though.
> 
> later... Jim  VE7RF
> 
> 
> 
> 
> --------------------------------------------------
> From: "Bob K6UJ" <k6uj at pacbell.net>
> Sent: Tuesday, January 17, 2012 8:13 AM
> To: "[TowerTalk]" <towertalk at contesting.com>
> Cc: "Jim Thomson" <jim.thom at telus.net>
> Subject: Sealing coax connectors
> 
>> Jim,
>> 
>> (I took the liberty of using a new subject for my response to this item in 
>> your posting in the "PL259 insertion loss" thread.)
>> 
>>> ##  and don't forget to use dow corning dc-4/5 on all the connectors, 
>>> including threads, pins, and center females.  The 7-16 is clearly
>>> the connector of choice for the bigger coax cables  [ it's ur only real 
>>> choice].   For the smaller cables, like 213-U, and LMR-400, the
>>> UHF QUALITY silver/teflon connectors are plenty good enough.  Type N for 
>>> any size cable is a pita.  Odd ball connectors like C...and also
>>> LC connector's are going out of vogue.
>>> 
>>> Later... Jim  VE7RF
>> 
>> 
>> Jim,
>> 
>> I havent used a silicone sealant in my connectors before but the Dow 
>> Corning silicone sounds like a good plan.  For outside connectors I wrap
>> with Scotch 2228 self sealing  tape, then wrap with scotch 88 tape, then 
>> finally brush on Scotch Coat.  This has worked well for outside 
>> connectors,
>> taking the connectors apart later on they are always nice and shiny.  I 
>> will try the Dow Corning silicone before the tape treatment.
>> One question though, can the connector be taken apart, cleaned up and 
>> reused after using the silicone ?  I normally wouldn't reuse the 
>> connectors
>> but if they were new connectors it would be nice to be able to tie into 
>> the connector again, for instance adding on a longer section of coax.
>> (I'm talking about the threaded connection, not taking them apart and 
>> resoldering)
>> 
>> Bob
>> K6UJ
>> 
>> 
>> 
>> 
>> 
> 
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