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" <fptowns...@earthlink.net>
To: "David Cutter" <d.cut...@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.cut...@ntlworld.com>
Sent: Oct 13, 2014 4:14 PM
To: Fred Townsend <fptowns...@earthlink.net>, elecraft@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
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