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Silver Plating Copper Tubing




 
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Author Topic: Silver Plating Copper Tubing  (Read 8560 times)
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aa5wg
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« on: August 08, 2011, 07:59:27 PM »

Hi to all:
Does anyone know of a company that can silver plate a 50 and 100 foot role of 1/8 (.125) and 1/4 (.250) inch outer diameter copper tubing.
The price has to be reasonable.
Chuck
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WBear2GCR
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« Reply #1 on: August 08, 2011, 08:09:57 PM »


I do not believe that a satisfactory plating job can be done when the tubing is in the rolled up form...

                _-_-bear
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KA2DZT
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« Reply #2 on: August 08, 2011, 08:14:00 PM »

Look in your local phone book for a company that does plating.  Do it fast before the price of silver goes up.

Gold today hit over $1700/oz
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k4kyv
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Don
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« Reply #3 on: August 08, 2011, 11:03:02 PM »

You are wasting your time and money to silver plate your RF coils. The conductivity of silver is only slightly higher than that of copper.  Silver plating gained its popularity largely because it is prettier than pure tarnished copper. Just use copper, and if you are worried about natural tarnishing from exposure to air, spray it with lacquer or varnish (IOW make it oxygen-free, but notice that "Copper, Deoxidized (Annealed)"  has higher resistivity than pure copperGrin)

http://www.eddy-current.com/condres.htm
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Don, K4KYV                                       AMI#5
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Patrick J. / KD5OEI
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« Reply #4 on: August 09, 2011, 12:22:29 AM »

I saw the chart but do you mean that my copper coils with an old dull finish are better than if I had polished them up and lacquered them? If so I'm glad to have a few really dirty old transmitters!
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« Reply #5 on: August 09, 2011, 01:41:06 AM »

Here is one way to do it.

73dg

73DG


* HamSilverPlating.jpg (137.68 KB, 971x562 - viewed 474 times.)
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aa5wg
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« Reply #6 on: August 09, 2011, 07:38:19 AM »

Don thank you for the chart.  Everyone thank you.  I still would like to get a good price.  The companies I contacted want to much.  I wonder how much   the antenna tuner and amplifier companies pay?
Chuck
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WD8BIL
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« Reply #7 on: August 09, 2011, 08:20:54 AM »

As Don said, but I'll add a qualifier, silver plating tank coils for operation below 50Mhz is a waste of time and money. Unless you plan on a lot of VHF work save your money and buy a tube/socket combination that'll give you more scrote. A tube with handles would be preferable!
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Jeff W9GY
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« Reply #8 on: August 09, 2011, 08:25:27 AM »

I have silver plated small pieces of copper with old )used up) photographic fixer.  The used fixer has silver disolved in it and can be plated out onto copper with an electric current.
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Jeff  W9GY Calumet, Michigan
(Copper Country)
Bill, KD0HG
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« Reply #9 on: August 09, 2011, 09:08:52 AM »

There's Cool-Amp silver plating powder.

Dip a moist towel into the powder and rub it into the copper. End result isn't as thick as an electroplating shop, but it suffices.

http://www.cool-amp.com/
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WA1GFZ
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« Reply #10 on: August 09, 2011, 09:28:48 AM »

I posted some links to silver plating supplies a couple months ago. It would cost you about $40 to do it yourself with the addition of a small variable power supply.
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KD7EDW
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« Reply #11 on: August 09, 2011, 09:35:28 AM »

It is pretty easy to replicate the Cool-Amp formula at home.  Checkout this website:   http://www.on7lr.org/special/ag/ag.htm    Places like Photographers Formulary or United Nuclear with sell the Silver Nitrate in small quantities.    

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k4kyv
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Don
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« Reply #12 on: August 09, 2011, 10:08:49 AM »

I saw the chart but do you mean that my copper coils with an old dull finish are better than if I had polished them up and lacquered them? If so I'm glad to have a few really dirty old transmitters!

I'm not so sure about that. I would think pure bright untarnished copper would have equal or slightly better conductivity than old tarnished stuff. It depends on exactly what they mean by "Copper, Deoxidized (Annealed)". Annealing means that the copper is heated to a red glow and allowed to cool, which softens it until it is "work hardened" back to near its original state. I first discovered this while brazing my radial ground system together. This all involves altering the crystallisation structure of the metal, but I'm not sure what that has to do with "de-oxygenation" or how it affects conductivity.

This might provide some insights regarding copper oxide:
Quote
Most metals, including copper and aluminum, form thin metal oxide film layers when exposed to air for even a brief time -- this is what makes a new penny turn dull after a few days or weeks. These oxide layers are so thin however that for all practical purposes they do not interfere with the conductivity across such layers."

http://answers.google.com/answers/threadview/id/397640.html

Silver plating would protect the copper from oxidation, but silver in contact with air also tarnishes very quickly. I have heard or read that silver oxide is just as good a conductor as untarnished silver, AND that silver oxide is such a poor conductor that it is practically a dielectric (whiskey tango foxtrot?).  I would just use plain copper, let it tarnish brown and not worry about it.


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Don, K4KYV                                       AMI#5
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w3jn
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« Reply #13 on: August 09, 2011, 11:05:25 AM »

Unfortunately silver tarnish is NOT silver oxide, it's silver sulfide which is a poor conductor.  Hence the rotten egg sulphur smell when you use Tarn-X or similar.
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« Reply #14 on: August 09, 2011, 02:36:24 PM »

JN
Don
et. al.

In the case of a coil (as opposed to a contact), I would think that a very thin layer of a good insulator (or at least a very poor conductor), like silver sulfide, would have essentially no effect. Presumably, the current, at very high frequencies, would travel through the layer of silver underneath the thin layer of (essentially insulating) silver sulfide.

Stu
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KM1H
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« Reply #15 on: August 09, 2011, 04:25:19 PM »

At 432 MHz silver plating may offfer a bit more efficiency but I wouldnt waste money on it. A FM Class C copper pipe 4CX250B cavity I built in the late 70's still shows the same efficiency. A 1500W 2M copper split plate amp was 62% efficient when I built it over 25 years ago and hasnt changed.

I aint into purty when it wastes my time and/or costs money Roll Eyes  I leave that up to the wimmin Grin
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AB2EZ
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"Season's Greetings" looks okay to me...


« Reply #16 on: August 09, 2011, 05:44:11 PM »

Carl

"At 432 MHz silver plating may offfer a bit more efficiency but I wouldnt waste money on it. A FM Class C copper pipe 4CX250B cavity I built in the late 70's still shows the same efficiency. A 1500W 2M copper split plate amp was 62% efficient when I built it over 25 years ago and hasnt changed. I aint into purty when it wastes my time and/or costs money   I leave that up to the wimmin."

Based on what I can infer from your postings... this sounds like a good strategy for you.

Stu
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KD7EDW
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« Reply #17 on: August 09, 2011, 05:56:08 PM »

I was just recently looking at my recently acquired BC-696-A transmitter and its silver plated front end.  If sliver plate doesn't add to the efficiency of the coil   - why did they silver plate instead of using the silver for silver nitrate in explosives?  I suppose that In my novice thinking, the answer maybe the size of the coil?   That is, a large diameter  coil made of large diameter tubing naturally has more "Q" - while a small coil made with wire has less "Q"? I have noticed this as well in variable capacitors - the smaller ones used for vfo's are more likely to be silver plated, where as the HV caps used for tuners and amps are simply bare aluminum or nickel plated.        
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KM1H
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« Reply #18 on: August 09, 2011, 09:56:59 PM »

Quote
Based on what I can infer from your postings... this sounds like a good strategy for you.

Stu

You know what they say about assumptions Stu, you just won the door prize.

Quote
I was just recently looking at my recently acquired BC-696-A transmitter and its silver plated front end.  If sliver plate doesn't add to the efficiency of the coil   - why did they silver plate instead of using the silver for silver nitrate in explosives?


Ive asked that question for ages and never got a satisfactory answer. One scenario is that some pointy headed academic wrote a long dissertion that it was required so the War Dept big wigs wrote memos to all their relatives to invest in silver.

At some frequency and at some power level it makes sense as well as for switch and relay contacts, some connectors, rotary inductors, and Im sure other things where a harder surface was required for longevity/reliability.

Quote
I have noticed this as well in variable capacitors - the smaller ones used for vfo's are more likely to be silver plated, where as the HV caps used for tuners and amps are simply bare aluminum or nickel plated.

A lot of small caps used by hams were WW2 and Korea military surplus, even in manufactured products. You dont see them much any more and very stable VFO caps use either a special alloy or copper and aluminum plates; no silver is involved. The varicap has just about replaced them too.

Carl
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aafradio
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« Reply #19 on: August 16, 2011, 03:21:48 PM »

I was just recently looking at my recently acquired BC-696-A transmitter and its silver plated front end.  If sliver plate doesn't add to the efficiency of the coil   - why did they silver plate instead of using the silver for silver nitrate in explosives?  I suppose that In my novice thinking, the answer maybe the size of the coil?   That is, a large diameter  coil made of large diameter tubing naturally has more "Q" - while a small coil made with wire has less "Q"?

Somewhere in the files I have a copy of some contract correspondence concerning the Navy ATB transmitter that RCA produced for aircraft.
http://aafradio.org/docs/atb-arb.html has an overview.  Seems that the contract specification required a minimum Q for the PA tank and loading coils, an unusual component of what was otherwise pretty much a straight performance spec.  Come the first article inspection model and the transmitter easily met the output and spectrum tests, but then they measured the Q of the coils...a little too low.  Despite extensive ranting and raving by RCA, the Navy stuck to its guns, and eventually RCA had to use solid silver wire to meet the specification, so there is a relationship of some sort.  That's apparently one reason the transmitter is now extremely uncommon...after the war many of them were bought to simply salvage the wire from the coils.

I don't believe the Navy ever attempted to use that clause again.

Please note that I have not dissected my ATB with a hack saw to confirm the use of solid silver... Shocked
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Mike  KC4TOS
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