[Elecraft] BNC v TNC

[David Cutter]

Fred

Yes, you are right, Vaseline does run like that, but I try to stay far away 
from silicon grease as it's the best adhesive-inhibitor known to man even 
one molecule thick layer!  I worked in a factory which banned it because of 
that.  I use silicon RTV (the non-acetic acid type).

We used to be advised not to plug 50 ohm coax into a scope because it was 
said it would damage the 75ohm panel connector, but that must have changed 
with the change of the centre pin dimension as someone said here.

David
G3UNA




----- Original Message ----- 
From: "Fred Townsend" <fptownsend at earthlink.net>
To: "David Cutter" <d.cutter at ntlworld.com>
Sent: Tuesday, October 14, 2014 12:40 AM
Subject: Re: [Elecraft] BNC v TNC


>
> Hi David:
>
> Yes I have seen counterfeit TNCs. The assembly I worked on had two BNC, 
> two TNC and one SMA. Only the SMA, which was receive only (GPS), did not 
> have problems. The connectors were cast and had mold marks. Resistance was 
> supposed to be a few milliohms but measured 10 times that. They were 
> inferior in just about every parameter. They had no manuafacture's mark at 
> all so impossible to trace beyound the Chinise distributer we bought them 
> from.
> Vaseline is good but will run a bit in hot sun. (Is that a problem in the 
> UK?) I use a silicon grease from 3M. It was listed as stopcock grease but 
> worked perfect at all temps. I like a silicon rubber tape or RTV (type 1) 
> for wrapping. RTV has the nice advantage it can be applied around water 
> without drying.
>
> 73
> Fred
>
> -----Original Message-----
>>From: David Cutter <d.cutter at ntlworld.com>
>>Sent: Oct 13, 2014 4:14 PM
>>To: Fred Townsend <fptownsend at earthlink.net>, elecraft at mailman.qth.net
>>Subject: Re: [Elecraft] BNC v TNC
>>
>>Hi Fred
>>
>>I wonder if you have come across counterfeit TNC connectors.  I would 
>>guess
>>that since these are not used in the mass computer industry then there is
>>less incentive for the counterfeiters to be interested.  The BNC is most
>>interesting because it's so easy to connect and disconnect, but for me 
>>it's
>>a size issue and I prefer the *improved* water resistance of the TNC.  I
>>left a mated pair out in a heavy downpour recently and found no water
>>ingress.  If I were doing it properly I would apply a little Vaseline
>>petroleum jelly on the thread.
>>
>>David
>>G3UNA
>>
>>
>>
>>
>>> Without sounding my horn too loudly I have servered on IEEE connector
>>> committees and been paid big bucks to solve the production line 
>>> problems.
>>> Counterfet connectors is too mild a term. There is some real crap out
>>> there and your eyeballs won't be able to detect it. Things like finish 
>>> and
>>> and spring tention problems can not be seen. I recall one particular
>>> connector that was causing a 2db measured loss over a prefered Kings or
>>> Amphenol connector. The imported brand X connector was available in both
>>> 50 and 75 ohm versions, both of which were unmarked. When actually
>>> measured with a TDR they both measured 62 ohms.
>>>
>>> Folks, life is too short to mess with S T U F F like this. Do you really
>>> have to touch the wet paint or believe the sign.
>>>
>>> 73, Fred, AE6QL
>>>
>>>
>