But then, maybe SILVER (AG) ! Silver is one heck of a conductor, and what,
pray , when it Oxidizes (AG - O) ? Turns out that the conductivity of
Silver Oxide is almost as great as SILVER! (but, as for the effeciency, ,
unless severe resistance (perhaps in a hi "Q" loading coil for a mobile)
Doubt would make much difference that could be detected! Jim NN7K

--
No trees were killed in the sending of this message. However, a large number
of electrons were terribly inconvenienced !


"H. Adam Stevens, NQ5H" wrote in message
...
Hi Roy;
It's worse than that: Copper will diffuse throught the gold and pile up on
the surface.
I showed that with an Auger microprobe at Motorola decades ago.
So to go to a gold surface, nickel is mandatory, then a thick gold
coating;
Too expensive!
It's not like the switch from aluminum to copper, which is a 2x
resistivity
improvement.
You just can't beat plain old copper.
73
H.
NQ5H

"Roy Lewallen" wrote in message
...
I've seen real-life cases with high-Q microstrip structures where gold
plating actually caused a significant lowering of efficiency. As you
point out, nickel is used as a barrier metal to prevent alloying of the
gold with the underlying copper. If the gold isn't at least several skin
depths thick, significant current flows in the nickel. Nickel is a
particularly poor RF conductor, very much worse than copper, because the
skin depth in nickel is decreased dramatically by its ferromagnetic
permeability. So, if you're able to calculate skin depth, and know what
you're doing, and are willing to use quite a bit of gold (particularly
necessary at HF and below) you can achieve efficiency with gold plating
that's pretty much indistinguishable from that of copper. If you don't
know what you're doing, it is possible to substantially degrade the
efficiency by gold plating. I'm sure somebody could be conned into
buying one, though.

Roy Lewallen, W7EL

Gary V. Deutschmann, Sr. wrote:

Hi Gang

Since the radiation of an antenna is done primarily on the surface of
the elements (or wire) would gold plating the elements increase the
efficiency of the antenna in any way?

Gold sounds expensive, but if thin enough, one ounce of gold could
plate an entire football field. Brass corrods, nickel is usually used
as the first plating before another metal like gold is plated over
that. If the cost for gold over the cost of brass is only about 1
buck per foot of element length, making cost not relavent to the
question. Would a gold plated antenna work better than aluminum or
nickel plated?

TTUL
Gary

Ah, finally, someone who knows what the conductivity of silver oxide is.
Although I believe silver sulfide is much more common than oxide, I've
been able to find the conductivity of the sulfide but not the oxides.
Just what are the conductivities of the silver oxides (AgO and Ag2O)?
Which are we most likely to find on the outsides of wires? Are they
really more common than the sulfide?

Roy Lewallen, W7EL

Jim wrote:
But then, maybe SILVER (AG) ! Silver is one heck of a conductor, and what,
pray , when it Oxidizes (AG - O) ? Turns out that the conductivity of
Silver Oxide is almost as great as SILVER! (but, as for the effeciency, ,
unless severe resistance (perhaps in a hi "Q" loading coil for a mobile)
Doubt would make much difference that could be detected! Jim NN7K

Roy Lewallen wrote:

Ah, finally, someone who knows what the conductivity of silver oxide is.
Although I believe silver sulfide is much more common than oxide, I've
been able to find the conductivity of the sulfide but not the oxides.
Just what are the conductivities of the silver oxides (AgO and Ag2O)?
Which are we most likely to find on the outsides of wires? Are they
really more common than the sulfide?

Roy Lewallen, W7EL


An interesting and eventually amusing link on silover sulfide


http://www.eecs.cwru.edu/misc/AMANDA...er_revised.doc

another:

http://www.brushwellman.com/alloy/tech_lit/sep02.pdf


and this:

http://nepp.nasa.gov/whisker/reference/tech_papers/chudnovsky2002-paper-silver-corrosion-whiskers.pdf

It is interesting that the NASA paper refers to silver sulfide as
non-conductive, while the first paper gives a short and tantilizing
tidbit about forcing it into conductivity.

Hope you find the links interesting!

- Mike KB3EIA -

Mike,

Thanks very much for the links. They furnished quite a bit of
information about silver, its alloys, and its salts, that I didn't know.
They do seem to support what I had thought about sulfide being more
common than oxide, and added chloride to the list of common tarnishes.
And maybe the reason for the elusiveness of information on the
conductivity of silver oxide is because of the strange nonlinear effects
reported in the first paper. Hopefully Jim will be able to fill us in
about that, since he apparently has some information on the oxides. I'm
frankly startled that any oxide can have conductivity within even a few
orders of magnitude of a good pure metal, so I hope he'll post the
information soon. One of the links notes that only silver alloys
(particularly with copper) tend to oxidize, so in order to get a coating
of silver oxide, you'd need to coat your wire not with pure silver, but
with an alloy that's somewhat more resistive than copper to begin with.
Does that mean, Jim, that the conductivity of the plated wire would
actually improve as it oxidizes?

A paper I read some time ago showed that silver plating nearly always
consists not of pure silver but of some alloy (as one of the links
pointed out), and nearly all those alloys have a conductivity less than
copper -- some, much less. So if you want to reap whatever benefit there
might be in silver corrosion products over copper ones, you'll have to
put up with lower conductivity in the uncorroded wire. Seems to me to
make more sense to use enameled or insulated copper wire to begin with,
but I guess some folks think the appearance of silver is worth the hassle.

The only resistivity information I have is for AgS, which is apparently
a common corrosion product, and its resistivity is about 100,000 times
as great as silver. This isn't necessarily bad, since both a perfect
conductor and a perfect insulator provide a lossless coating. The loss
incurred by conductors of intermediate quality depends on the frequency
and coating thickness, so it can be hard to draw conclusions about what
compound might be better than another except in a specific case.

Roy Lewallen, W7EL

Mike Coslo wrote:

Roy Lewallen wrote:

Ah, finally, someone who knows what the conductivity of silver oxide
is. Although I believe silver sulfide is much more common than oxide,
I've been able to find the conductivity of the sulfide but not the
oxides. Just what are the conductivities of the silver oxides (AgO and
Ag2O)? Which are we most likely to find on the outsides of wires? Are
they really more common than the sulfide?

Roy Lewallen, W7EL



An interesting and eventually amusing link on silover sulfide


http://www.eecs.cwru.edu/misc/AMANDA...er_revised.doc

another:

http://www.brushwellman.com/alloy/tech_lit/sep02.pdf


and this:

http://nepp.nasa.gov/whisker/reference/tech_papers/chudnovsky2002-paper-silver-corrosion-whiskers.pdf


It is interesting that the NASA paper refers to silver sulfide as
non-conductive, while the first paper gives a short and tantilizing
tidbit about forcing it into conductivity.

Hope you find the links interesting!

- Mike KB3EIA -