Do you guys think it is OK to clean silver-plated RF connectors with 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:
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.
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.
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.
ry
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.
"Michael A. Terrell" wrote in news:WJqdnchDr5NJIgnRnZ2dnUVZ snipped-for-privacy@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;-)
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.
-- Politicians should only get paid if the budget is balanced, and there is enough left over to pay them.
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. ;-)
-- Politicians should only get paid if the budget is balanced, and there is enough left over to pay them.
"Michael A. Terrell" wrote in news:F_mdnfHvgNt6bQnRnZ2dnUVZ snipped-for-privacy@earthlink.com:
[snip]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.
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;-)
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. * ******************************************************************
Yes. That's what happens when I get less than three hours sleep. :(
-- Politicians should only get paid if the budget is balanced, and there is enough left over to pay them.
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.
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).
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
...
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
Of course. Any time you're troubleshooting, the first step is to reseat all the connectors. :-)
Cheers! Rich
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.
*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
How about the aluminium and baking soda treatment?
Joop
"Tim Williams" wrote in news:i73nom$a73$ snipped-for-privacy@news.eternal-september.org:
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
Silver tarnish is silver sulfide, which IIRC is conductive.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.