14845Re: AW: AW: [SDRSharp] ebay antenna
- Jun 24, 2014I stand corrected! Either the information I received was incorrect or I mis-remembered it! That's a word...isn't it? :-)
73 - Ken
> On Jun 24, 2014, at 8:27 PM, "jdow jdow@... [SDRSharp]" <SDRSharp@...> wrote:
> This prompted me to do a little research.
> Silver oxide is non-conductive except in certain forms such as used in silver
> zinc batteries. It doesn't form easily.
> Silver sulfide is the usual surface film of tarnish seen most often. It, too,
> is a non-conductor in bulk. In practical terms on relay contacts it increases
> the contact resistance by a factor of about 3. So it's not bad but it's not
> good either.
> Copper oxide and copper sulfide are less well behaved.
> In antennas you can actually end up with better performance over time with
> anodized aluminum. It's surface doesn't conduct. So you have a very thin
> layer of dielectric over the conducting aluminum. Add a nice layer of Krylon
> sprayed over it all and the antenna will last a long time with little
> change in performance over the years. You simply use a larger conductor to
> make up for the poorer conductivity. (Krylon over silver or copper is not as
> nicely behaved. I believe it may have sulfur in it. Many people use these
> combinations anyway. So it may not be as bad as I suspect.)
> In constructing the antenna keep screws and bolts out of the electrical path
> as much as possible. They are not as well behaved, either.
> And, yes, I mucked up in my memory about gold's conductivity. I for some
> idiot reason thought it was further down than third place in the usual
> scale (pre graphene).
>> On 2014/06/24 14:38, Ken Alexander k.alexander@... [SDRSharp] wrote:
>> Seems to me I read somewhere that one of the advantages of silver is that not
>> only is it a good conductor, but the oxide (tarnish) coating that forms is an
>> equally good conductor. I'm going from memory, so feel free to shoot down this
>> assertion if you know better. *:) happy
>> Gold of course doesn't oxidize. Another great reason it makes a good contact
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