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High Q UHF coils and lines

 

Hi! I understand VHF / UHF coils are silver plated, not because silver has a slightly lower resistivity than copper, but more because silver oxide is conductive, whereas copper oxide not. This statement sounds a little strange to me, because silver oxide has a quite higher resistivity than the pure metal anyway. But let's leave it there.
My question is: wouldn't it be far superior to use enamel copper wire, possibly adding a perfectly airtight lacquer on top of the enamel? That way Q would be preserved along the years better than with silver plating.
Obviously I must be wrong, because otherwise nobody would take pains to apply the silver.
Can anybody clarify this?
Kind regards
Daniel Perez LW1ECP
 


I've got a considerable pile of WW II RF stuff Dad bought on Radio Row (Cortlandt St, torn down to build the World Trade Center) in NYC after the war. I don't recall ever seeing a silver plated coil that was tarnished, so I must presume that there was some coating applied over the silver.
Switches and such are commonly tarnished.

One of my winter projects is to move and inventory the pile so I'll try to remember to take some pictures. If anyone is interested in buying such stuff send me a PM. Dad bought cases of really high quality parts. I need to sell this stuff off as it exceeds anything I could ever use up.

The high power RF stuff is amazing. Steatite coil forms and silver plated wire. Very bulky, but it had to be big to allow the high voltages. The tubes in the standard B-17 radios had a 1500 V plate rating!. These have become *the thing* for audiophool amplifiers and the tubes sell for $300-400 each. Dad left me 23 of those tubes :-)

For anyone interested in tube stuff, I've got a rather large quantity of a tube which is basically a 6L6 with a 3 V filament in addition to a lot of other well chosen general purpose tubes. So if you want to make an Ameco AC-1, my only station transmitter, it's a bargain relative to a 6L6.

Thanks for posting. I'm currently struggling with writing some comments about the QEX WSPR QRN paper in the 9-10/20 issue. I'm very intrigued by the work, but not entirely sure I know enough about the ionosphere yet. My career was spent looking down, not up.

Have Fun!
Reg


On Thursday, October 22, 2020, 07:52:22 PM CDT, Daniel Ricardo Perez via groups.io <danyperez1@...> wrote:


Hi! I understand VHF / UHF coils are silver plated, not because silver has a slightly lower resistivity than copper, but more because silver oxide is conductive, whereas copper oxide not. This statement sounds a little strange to me, because silver oxide has a quite higher resistivity than the pure metal anyway. But let's leave it there.
My question is: wouldn't it be far superior to use enamel copper wire, possibly adding a perfectly airtight lacquer on top of the enamel? That way Q would be preserved along the years better than with silver plating.
Obviously I must be wrong, because otherwise nobody would take pains to apply the silver.
Can anybody clarify this?
Kind regards
Daniel Perez LW1ECP

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