Yet another What Is This thread

[tryppyr]

Sometimes I run across things that seem to come from the dark ages. This is one such. Came in a Semiconductor Grab Bag.

Any clues?

 

[(*steve*)]

It could be a resonator, but that's not a semiconductor...

(I'm guessing now)

 

[davenn]

or a ceramic filter, in-gnd-out

( it may not have belonged in a semi. grab bag)

Dave

 

[tryppyr]

I'm not sure I can provide many more clues. I took out the multimeter and checked all combinations of the three pins. The needle never moved (yes, it's an analog meter).

Any thoughts on how I could test this to get a better read on what it is? Not that I ever plan to use it... just intellectual curiosity.

 

[davenn]

If you had a spectrum analyser with a RF sweep generator, you could sweep it across a freq range and see the results on the spec an. it would confirm the filter idea and would tell you its centre freq

Dave

 

[KrisBlueNZ]

I've never seen anything like it, but I guess it could be a dual capacitor in a single package.

If the markings mean that the capacitors are 87 pF and 10 pF (not likely, but just for illustration) it could be something like:

1 -------| |--------2--------| |------3
. . . . 87 pF . . . . . 10 pF

In that case, if you measure the capacitance between each pair of pins, you would measure the following capacitances:

1 to 2: 87 pF
2 to 3: 10 pF
1 to 3: a bit less than 10 pF (capacitors in series are like resistors in parallel).

This is only a wild guess!

 

[tryppyr]

I put it on my capacitance meter. Drumroll please...

1-2: 1.814 nF
2-3: 1.834 nF
1-3: 0.211 nF

 

[KrisBlueNZ]

Hmm. That doesn't make much sense. If it was two 1.8 nF capacitors with a common terminal, you would measure 0.9 nF between pins 1 and 3. But I guess this does imply that it contains capacitance.

You could try asking on a vintage electronics forum - perhaps vintage radio. There's probably someone out there who knows what it is.

 

[tryppyr]

I do love a mystery. I'll check with the antique radio folks.

 

[tryppyr]

The early opinion from the radio forum is:

Actually that is an R-C network, probably a vertical integrator, based upon the Zenith 87- prefix. Somewhere there was a chart showing the values of the internal parts for the various Zenith 87- integrators.

 

[KrisBlueNZ]

You measured resistance across all combinations of pins and they were all open circuit, right? In that case it could not be an R-C integrator... But this guy sounds like he knows what he's talking about...

 

[tryppyr]

There is still some discussion about it going on. The latest to opine about it stated:

That package style, like a regular disc ceramic cap but with three leads, was commonly used for double bypass caps.

The middle lead was common to both capacitors, and connected to ground.
The other two leads then provided two independent capacitors, both to ground.

Obviously the same physical package could be used for other circuit configurations.

But elsewhere on the forum I saw a post specifically calling out the specs of an 87-10, showing a resistor value across two legs and a capacitance value across a different pair.

And yes, I confirmed with a different meter that no pairing of the leads shows measurable resistance.

 

[KrisBlueNZ]

I found your other thread at http://www.antiqueradios.com/forums/viewtopic.php?f=6&t=235796

Several people there have said that these components are notoriously unreliable. That could easily explain the fact that you don't measure any continuity across any combination of the wires. A second person confirmed that it's probably a Zenith R-C device with an 87- prefix. I suspect they're right. You might as well throw it away.

 

[tryppyr]

Yes, I probably should. I certainly have no use for it. Maybe my wife can use it to make something arty-crafty.