Tarn-X and high-frequency silver-plated RF connectors
mpm
Tarn-X?
Think: 2 GHz 7/16" DIN connectors used in the cellular & PCS industry
(towers).
Here's the MSDS; I don't recognize the chemicals:
Link: http://www.hescoinc.com/msds/comtx4.pdf
If OK to use, should one also clean any Tarn-X residue with isopropyl
alcohol afterwards, or is that really necessary?
I'm asking because sometimes these connectors come "new" from the
factory covered in silver tarnish and other crud. Thanks.
PeterD
wrote:
Back when I was in the USAF, we used a lot of silver plated RF
connectors. The rule was simple: never, ever try to clean them, the
'tarnish' is quite conductive and will not affect performance.
Michael A. Terrell
Bullshit. It has more resistance than the silver alloy, and can
cause incorrect readings, or the connector to overheat. I guess that
you've never seen a burnt flange on a piece of wave guide?
We used 91% Isopropyl alcohol and Q-tips to remove as much of the
oxide as we could.
--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
mpm
wrote:
> PeterD wrote:
>
> > On Fri, 17 Sep 2010 19:58:51 -0700 (PDT), mpm <mpmill...@aol.com>
>
> - Show quoted text -
What about for PIM noise? (Passive Intermodulation).
Does tarnish cause or exacerbate PIM?
Cleaning seems to make a difference, but cleaning a "clean" connector
probably does as well.
Often, just the disassemble/reassemble is enough to improve PIM. Very
touchy stuff when you're looking for -140 to -150 dBc.
Hammy
news:WJqdnchDr5NJIgnR...@earthlink.com:
Yes I agree they should be kept clean. When you figure all the effort
gone into a matching network any imbalance would cause a loss in signal
strength at minumum.
An oxidised coax BNC or SMA not sure what their useing up there on the
drop to my house was the source of intermittent internet connection
issues for me not to long ago and I think thats only around 900MHz the
higher the frequency likely the more critical the interconnects.
Mind you I could be wrong just my opinion.I havent touched RF in 5 years
or so. I dont have the cash for VNA's and spectrum anaylizers and
such;-)
Michael A. Terrell
We never used silver plated for low level signals. Only Nickel or
Gold.
Silver oxide is a conductor, but it is also a weak semiconductor that
can rectify stray RF. You know that any resistance in the shield nac
cause all kinds of odd problems.
The worst offender for me were in the old 'Bird 43' RF watt meters
with a low power slug in the 30 to 76 MHz range. I used them in QA
testing on the PRC-77 manpack radios. Every month or so I used a paper
towel to buff away the oxide, rather than call the characters in the
metrology lab.
Michael A. Terrell
> such;-)
Direct PC, or similar? I thought they were still using 'F'
connectors?
I'll give you a 'repairable' Polarad for the cost of shipping. It's
over 200 pounds, though. ;-)
Hammy
[snip]
>> >
>> >
>>
>> Yes I agree they should be kept clean. When you figure all the effort
>> gone into a matching network any imbalance would cause a loss in signal
>> strength at minumum.
>>
>> An oxidised coax BNC or SMA not sure what their useing up there on the
>> drop to my house was the source of intermittent internet connection
>> issues for me not to long ago and I think thats only around 900MHz the
>> higher the frequency likely the more critical the interconnects.
>>
>> Mind you I could be wrong just my opinion.I havent touched RF in 5 years
>> or so. I dont have the cash for VNA's and spectrum analyzers and
>> such;-)
>
>
> Direct PC, or similar? I thought they were still using 'F'
> connectors?
I'm not sure what they use. He tested my signal strentgth and it was down so he checked all the interconects and found the connector at
the drop was oxidised. Once he changed it my signals went back-up and I havent had an issue yet. Well he was here though I had him
change all the coax from the drop to the splice in the house and change the splice.;-) Shaws pretty good for stuff like that; no charge
and quick.
>
> I'll give you a 'repairable' Polarad for the cost of shipping. It's
> over 200 pounds, though. ;-)
>
Interesting but considering the shipping rates for 5lbs I dont think I want to know what they would charge for 200lbs!;-)
At the moment I'm haveing enough fun trying to program a PIC16F887 for inteligent control of an electronic load. Thats got my hands full
enough for the time being. I have the analog part done the programing part is always the bitch for me;-)
Sergey Kubushyn
It is _NOT_ silver oxide that forms that black tarnish. It is silver
_SULFIDE_ .
---
******************************************************************
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
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Michael A. Terrell
Yes. That's what happens when I get less than three hours sleep. :(
WallyWallWhackr
Silver Oxide is conductive. No need to remove it, and a fine patina
of
it is always a good thing., when it isn't pristine, which they rarely
are after
a short period.
No need to fuss with it at all.
whit3rd
> Tarn-X?
I'm thinking, no. The Tarn-X is intended to reduce AgS (sulphide
is the black 'tarnish'), but not to enhance conductivity. Mechanical
cleaning to remove loose material (or even just reseating the
connector) suffices. If there's any residue from the 'cleaner'
on the insulators, that's BAD; for anything critical, use
a low-residue cleaner (alcohol good, Freon TF better).
Rich Grise
> Do you guys think it is OK to clean silver-plated RF connectors with
> Tarn-X?
Absolutely yes; I've seen it in action. The tarnish just disappears,
and the silver is "none the worse for wear." :-)
I'd be interested in your experience if you simply dip them, rather
than use a rag or Q-tip or whatever.
Cheers!
Rich
Rich Grise
> On Fri, 17 Sep 2010 19:58:51 -0700 (PDT), mpm <mpmi...@aol.com>
>
>>Tarn-X?
>>I'm asking because sometimes these connectors come "new" from the
>>factory covered in silver tarnish and other crud. Thanks.
>
> Back when I was in the USAF, we used a lot of silver plated RF
> connectors. The rule was simple: never, ever try to clean them, the
> 'tarnish' is quite conductive and will not affect performance.
I was in the USAF too, and I think that rule was to keep the grunts
(of which I was one) from using sandpaper or wire brushes or scouring
powder.
When I was in Okinawa, ca. 1970's-ish, I had a buddy down the hall who
was a ham. They (the commander) had let him install an antenna tower and
20M quad antenna on the roof of the dorm!
Anyway, back then in Okinawa, the amount of surplus electronics available
for a song was mind-bogging. I watched this guy build a 1KW linear from
parts he got entirely from surplus WWII schtuff, except for the 4-400A
and its socket, which I stole for him out of bench stock.
One of the surplus Xmtrs had a beautiful tank coil, about 2.5" dia, by
about 6" long, of about 3/16" silver-plated (or maybe solid silver!)
tube that was almost all black on the outside.
As has been noted, not only is the tarnish almost as conductive as
silver itself, but it's really easy to shine up chemically, with
Tarn-X or even Brasso.
This idiot SANDPAPERED it! "What? You're a ham, and you've never
heard of the skin effect?"
Well, the thing _did_ work - it was grounded-grid, so what could go
wrong? ;-P
Cheers!
Rich
Rich Grise
> Often, just the disassemble/reassemble is enough to improve PIM. Very
> touchy stuff when you're looking for -140 to -150 dBc.
Of course. Any time you're troubleshooting, the first step is to reseat
all the connectors. :-)
Cheers!
Rich
mpm
On our last job, we were supplied jumpers that looked like they'd been
sitting in a warehouse for years.
Figuring we had little at risk, we gave Tarn-X a try.
Did a great job! But ultimately, we swapped out all the jumpers for
other reasons unrelated to their RF performance. (They were just too
long for the job.)
Anyway, we used Q-Tips in an attempt to keep the Tarn-X away from the
coax dielectric.
I think dipping them could cause problems (?)
Although, on a 7/16" DIN (male or female) connector, you could
probably dip them just fine, since the dielectric is pretty far up
inside the connector shell.
Tim Williams
news:pan.2010.09.18....@example.net...
> As has been noted, not only is the tarnish almost as conductive as
> silver itself, but it's really easy to shine up chemically, with
> Tarn-X or even Brasso.
*Cough*,
If the tarnish is nonconductive, it isn't carrying any current.
Therefore, the metal underneath is carrying the current. Since there's
still plating under the tarnish, nothing funny happens.
If the tarnish is conductive, it has fairly high resistivity. Therefore,
the skin depth is large, and little current flows in it. Almost all the
current flows in the metal surface.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
Joop
wrote:
How about the aluminium and baking soda treatment?
http://il.youtube.com/watch?v=CsKLcc13WBo
Joop
Jim Yanik
news:i73nom$a73$1...@news.eternal-september.org:
> "Rich Grise" <rich...@example.net> wrote in message
> news:pan.2010.09.18....@example.net...
>> As has been noted, not only is the tarnish almost as conductive as
>> silver itself, but it's really easy to shine up chemically, with
>> Tarn-X or even Brasso.
>
> *Cough*,
>
> If the tarnish is nonconductive, it isn't carrying any current.
> Therefore, the metal underneath is carrying the current. Since
> there's still plating under the tarnish, nothing funny happens.
>
> If the tarnish is conductive, it has fairly high resistivity.
> Therefore, the skin depth is large, and little current flows in it.
> Almost all the current flows in the metal surface.
>
> Tim
>
I believe silver oxide is resistive.
I'd like to add that if you use Tarn-X,you rinse with WATER,then you can
use 90%IPA to dry it off.
I used Tarn-X all the time at TEK to clean off silver plated switches in
500 series scopes.Followed by a spray bath in the wash rack and 3 days in a
drying oven.
--
Jim Yanik
jyanik
at
localnet
dot com
k...@att.bizzzzzzzzzzzz
>"Tim Williams" <tmor...@charter.net> wrote in
>news:i73nom$a73$1...@news.eternal-september.org:
>
>> "Rich Grise" <rich...@example.net> wrote in message
>> news:pan.2010.09.18....@example.net...
>>> As has been noted, not only is the tarnish almost as conductive as
>>> silver itself, but it's really easy to shine up chemically, with
>>> Tarn-X or even Brasso.
>>
>> *Cough*,
>>
>> If the tarnish is nonconductive, it isn't carrying any current.
>> Therefore, the metal underneath is carrying the current. Since
>> there's still plating under the tarnish, nothing funny happens.
>>
>> If the tarnish is conductive, it has fairly high resistivity.
>> Therefore, the skin depth is large, and little current flows in it.
>> Almost all the current flows in the metal surface.
>>
>> Tim
>>
>
>I believe silver oxide is resistive.
Silver tarnish is silver sulfide, which IIRC is conductive.
mpm
<k...@att.bizzzzzzzzzzzz> wrote:
> On Sun, 19 Sep 2010 12:05:23 -0500, Jim Yanik <jya...@abuse.gov> wrote:
> >news:i73nom$a73$1...@news.eternal-september.org:
>
> >> "Rich Grise" <richgr...@example.net> wrote in message
> >>news:pan.2010.09.18....@example.net...
> >>> As has been noted, not only is the tarnish almost as conductive as
> >>> silver itself, but it's really easy to shine up chemically, with
> >>> Tarn-X or even Brasso.
>
> >> *Cough*,
>
> >> If the tarnish is nonconductive, it isn't carrying any current.
> >> Therefore, the metal underneath is carrying the current. Since
> >> there's still plating under the tarnish, nothing funny happens.
>
> >> If the tarnish is conductive, it has fairly high resistivity.
> >> Therefore, the skin depth is large, and little current flows in it.
> >> Almost all the current flows in the metal surface.
>
> >> Tim
>
> >I believe silver oxide is resistive.
>
> Silver tarnish is silver sulfide, which IIRC is conductive.
>
>
>
> >I'd like to add that if you use Tarn-X,you rinse with WATER,then you can
> >use 90%IPA to dry it off.
> >I used Tarn-X all the time at TEK to clean off silver plated switches in
> >500 series scopes.Followed by a spray bath in the wash rack and 3 days in a
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
My question is not so much about the conductivity of the silver
tarnish.
I'm concerned about all those little semiconductor discontinuities
that "probably" generate excessive passive intermodulation (PIM). No
matter how conductive the tarnish might be, it's not silver-on-silver
mating surfaces. And through experimentation, we do find that
excessive tarnish (which could include other crud) does cause PIM
failures.
The client wants -150 dBc (150 dB below a 20-watt carrier).
-140 is achievable with some effort. But to get -150 reliably, we
generally only see that on mating surfaces that are squeaky clean!
Thus, my question about Tarn-X. As a labor saver.
Not whether tarnish is conductive. But I think I have a book in the
library that might provide this number. If I can find it, I'll post
it.
Tim Williams
news:d1781ab6-6aee-488a...@y3g2000vbm.googlegroups.com...
> Not whether tarnish is conductive. But I think I have a book in the
> library that might provide this number. If I can find it, I'll post
> it.
I would be interested to see the real numbers on Ag2O and Ag2S. I'd also
be very curious to know if it varies much with doping (like most compounds
in this area of the periodic table, they should be semiconductors of some
capacity).