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@pacbell.net>
> Sent: Tuesday, January 17, 2012 8:13 AM
> To: "[TowerTalk]" <towertalk@contesting.com>
> Cc: "Jim Thomson" <jim.thom@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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