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 Post subject: Silver plated coax connectors
PostPosted: May Sun 15, 2022 3:16 pm 
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I have received a LOT of coax antenna connectors that are silver and are tarnished, some badly. Do they need to be polished or is the plating conductive even if tarnished? Carl

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Last edited by Cwebs on May Sun 15, 2022 3:52 pm, edited 2 times in total.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 3:46 pm 
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For any significant power level the resistance of the tarnish is insignificant.

Dale H. Cook, Retired AM/FM/TV Chief Engineer, Roanoke/Lynchburg, VA
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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 8:04 pm 
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Thank you Dale.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 9:28 pm 
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Greetings to Cwebs and the Forum:

It depends on the tarnish. Most tarnish is silver oxide, which is just about as conductive as the pure metal and so is not a problem. Silver sulfides, however, are another kettle of fish entirely. Exposure of silver to air pollution (which often contains significant amounts of sulfuric acid) will create corrosion that is non-conductive and will seriously interfere with the connector's performance.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 10:00 pm 
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How best to remove it?


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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 10:16 pm 
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Tarnish (black) is generally silver sulfide, not silver oxide (which is white or gray). SIlver sulfide is not a good conductor.


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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 10:20 pm 
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w3jn wrote:
Tarnish (black) is generally silver sulfide, not silver oxide (which is white or gray). SIlver sulfide is not a good conductor.

Thankfully my tarnish is gray.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 10:47 pm 
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bfo wrote:
How best to remove it?

Because coaxial connector are silver plated you should not use common silver polishes. Some contain an abrasive which is suitable for sterling but will reduce the thickness of silver plating. Others make the silver sulfide soluble which also reduces the thickness of the plating. A mixture of 1 cup of baking soda to 1 gallon of boiling water poured into an aluminum foil lined pan will do the trick by chemically detaching the sulfide radicals from the silver. Although some of the sulfide radicals remain in solution most of them will bond with the aluminum foil. Cleaning should be followed with a thorough rinsing.

I have used this for silver-plated tablewear, but I don't think I would use it for most coaxial connectors. I have used it for GR 874 connectors because I have a GR-874TOK toolkit for disassembling and reassembling the 874 series, letting me subject only the plated parts to cleaning.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Sun 15, 2022 10:57 pm 
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Personally, I would think that since the usual coax connector contact surfaces are sliding contacts (center pins, threads, bayonet twist locks) the tarnish probably gets wiped from the contacting surfaces. I have not studied that, however.


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 Post subject: Re: Silver plated coax connectors
PostPosted: May Mon 16, 2022 12:17 am 
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I have thought that wiping might help, but have not studied it.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Mon 16, 2022 5:44 pm 
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bfo wrote:
How best to remove it?

Get a bottle of Tarn-X. It removes silver tarnish very well and quickly.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Mon 16, 2022 8:50 pm 
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ChrisW6ATV wrote:
Get a bottle of Tarn-X. It removes silver tarnish very well and quickly.

By removing the tarnish Tarn-X also removes some of the plating by dissolving and removing the silver sulfide. The only satisfactory way to remove silver sulfide tarnish is to reverse the chemical reaction that created the tarnish with another chemical reaction that detaches the sulfide radicals from the silver atoms. That leaves the original silver plating intact.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Tue 17, 2022 1:04 am 
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A pencil eraser works well to clean silver tarnish (grey). But if it is grey I wouldn't worry about it. I only clean where it needs to be soldered. As noted, it is almost as good a conductor. Just use 'em and be happy.


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 Post subject: Re: Silver plated coax connectors
PostPosted: May Tue 17, 2022 4:50 am 
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I thought it was supposed to be washing soda that you put in the water with the aluminum foil, not baking soda. ?

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Tue 17, 2022 12:03 pm 
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Geoff Fors wrote:
I thought it was supposed to be washing soda that you put in the water with the aluminum foil, not baking soda. ?

It is baking soda (sodium bicarbonate) which should be used because it is a milder alkali than washing soda (sodium carbonate).

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Tue 17, 2022 12:10 pm 
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All good info, Thanks guys, Carl

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Tue 17, 2022 1:52 pm 
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Location: Kingwood, Texas
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They’ll be fine just like they are. Don’t sweat the tarnish.


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 Post subject: Re: Silver plated coax connectors
PostPosted: May Tue 17, 2022 4:15 pm 
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nothing more than a slight amount of Dexoit on the RF current bearing surfaces.. other than that, do not sweat it. it can be an IMD issue in some unique repeater applications. I would not use any chemicals that result in conductive leakage paths!!!!

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Wed 18, 2022 3:49 am 
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The correct approach is to replace the connector. If any sort of cleaning solution gets into the cable itself, you will be worse off than you were to start.

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 Post subject: Re: Silver plated coax connectors
PostPosted: May Wed 18, 2022 11:19 am 
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In post #1 the OP said he came upon lots of coax connectors, not cables.
But never mentioned the style of connector, or application he had in mind for their usage.


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