# unknown electronic parts (microwave radio)



## joubjonn (Mar 5, 2014)

i have a few of these, see two pics below. have no idea what they are, the circles parts look like they might be very old MLCC's, some kind of surface mount? and the other parts look like they have silver. i tried to do a google search and a search on here and couldn't find anything. pretty sure they are from 70's microwave radio/transmission units. wondering if they are worth saving, have not tried to do any testing yet, thought maybe someone on here had some experiance with these.

thanks!
-Jon


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## necromancer (Mar 5, 2014)

looks like mini silver spark plugs


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## Geo (Mar 5, 2014)

http://www.bing.com/images/search?q=stud+mounted+diode&go=&qs=n&form=QBIR&pq=stud+mounted+diode&sc=1-18&sp=-1&sk=

More than likely, its a rectifier diode. looks silver plated. The round button objects are silver plated ceramic.


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## joubjonn (Mar 5, 2014)

thanks!! i really appreciate it. the problem was i had no idea what to search, now i do! worth retrieving the silver on those or is it too thin to mess with?


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## rucito (Mar 5, 2014)

Тhe first picture is more like duct capacitor


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## Geo (Mar 5, 2014)

rucito said:


> Тhe first picture is more like duct capacitor



Can you give some examples and is this the technical name or a misnomer as i cant find any information on "duct capacitor".


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## Geo (Mar 5, 2014)

joubjonn said:


> thanks!! i really appreciate it. the problem was i had no idea what to search, now i do! worth retrieving the silver on those or is it too thin to mess with?



When weather will allow, I am working on a silver stripping cell using sodium thiosulfate that should make stripping silver plate profitable. Never toss or sell for copper any precious metal bearing components.


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## rucito (Mar 5, 2014)

Feed through capacitor


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## joubjonn (Mar 5, 2014)

I'll hold on to them. I have a few silver plated (and gold plated) BNC blocks, the ones with 4 screw holes.


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## g_axelsson (Mar 5, 2014)

Rucito is correct, it's an EMI feed through filter, for low frequency signals and power and usually have a small capacitor built in.

Smash it with a hammer and you will find out that it is basically a wire that is isolated from the metal body. It could go through a ferrite bead, have an integrated capacitor or both forming a crude low pass filter. It keeps high frequency noise out or signals inside RF (radio frequency) devices.

The dead giveaway is that the wire is isolated from the body at both sides. A diode almost always have one side connected to the body and usually only ends in a bolt.

Example : EMI Feedthrough Filters 470pF
Göran


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## joubjonn (Mar 6, 2014)

I just took apart an old microwave transmitter. heavy thing, about 40 pounds. anyway it had 3 solid silver (plated?) blocks attached to some aluminum boxes with coax cables going in and out. silver blocks weigh about 100 grams. they are very tarnished on the outside. the underside that was attached to the unit is shiny clean. anyone ever see any solid
silver in a microwave radio ? I'll post a pic in the
morning. 


it's also full of gold plated coax ends. a bunch of them. I'm going
to make a mini sulfuric cell just for those to see the yield.


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## g_axelsson (Mar 7, 2014)

Always silver plate, never massive.

There is something that's called the skin effect. It means that radio and micro waves only travels on the surface on a conductor, not in the center. The higher the frequency the less deep the signal penetrates. That's why you often see silver plate in RF circuits.

Göran


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## joubjonn (Mar 7, 2014)

I was just reading about that last night before bed! also why many high power lines are aluminum and not copper because it's not effected by the skin effect as much. really interesting stuff. opposing magnetic fields and what not. sometimes I wish I switched majors in college to EE instead of ME. however a lot of my friends and my college girl friend were EE's (Kettering University Flint, MI aka the General Motors Institute) and I remember the nightmares they had and the bad prof's.


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