Author Topic: Identification help of soviet passive component  (Read 1189 times)

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Offline VtileTopic starter

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Identification help of soviet passive component
« on: January 29, 2022, 09:38:12 pm »
Hi.

I do have a handfull of these components (see pictures) past 20+ years or so. I again found the old can I have them in.

My problem is that I just can't identify or measure them. The resistance seems to be over 1Gohms and even the capacitance seems to be that small that I do not have any even close to reliable measuring device in my disposal. I just were measuring roughly 0.5 pA with 10Vdc exidation voltage, but again I'm pushing my equipment on its limit.

Anyone have idea, I have no other idea than that they are from old Riga radio factory, by the story told when they were handed to me.
 

Offline rob77

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Re: Identification help of soviet passive component
« Reply #1 on: January 29, 2022, 09:41:49 pm »
that should be a capacitor.. probably you can't measure because it's only 15pF
 

Online ataradov

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Re: Identification help of soviet passive component
« Reply #2 on: January 29, 2022, 09:52:55 pm »
Those are capacitors and they are not great. Their real value is in the silver and other precious metal contents. If you can get a lot of them, they pay well. Their plates are made out of pure silver.
« Last Edit: January 29, 2022, 09:57:15 pm by ataradov »
Alex
 

Offline BrokenYugo

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Re: Identification help of soviet passive component
« Reply #3 on: January 29, 2022, 09:56:57 pm »
15pf 10%? Parallel the device in question with 100pf if you don't have anything that reads low enough.
 

Offline VtileTopic starter

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Re: Identification help of soviet passive component
« Reply #4 on: January 29, 2022, 10:01:16 pm »
Ok. Thanks.

That is what I were thinking - since they do seem to have less reactance than resistance - but could not verify properly.

A trash more or less, I have a about a big handfull of those so not worth to try sell / salvage.
 

Offline Vovk_Z

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Re: Identification help otf soviet passive component
« Reply #5 on: January 29, 2022, 10:02:12 pm »
It is a capacitor. 15 pF +-10 pF (with all temperature range).
Temperature coefficient is not larger than minus 1500 ppm.
 

Offline VtileTopic starter

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Re: Identification help of soviet passive component
« Reply #6 on: January 29, 2022, 10:08:18 pm »
15pf 10%? Parallel the device in question with 100pf if you don't have anything that reads low enough.
I think I did years ago measure them with classic sine generator & scope setup with series resistor, but again all I remember that phase shift was that low that it could have been the wires in measuring setup, then I did throw the can again at the bottom storage box.
 

Offline VtileTopic starter

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Re: Identification help otf soviet passive component
« Reply #7 on: January 29, 2022, 10:18:58 pm »
It is a capacitor. 15 pF +-10 pF (with all temperature range).
Temperature coefficient is not larger than minus 1500 ppm.
Thank you. Is the M1500 marking for that "minus 1500ppm" I would assume -1500ppm/K ?
 

Online ataradov

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Re: Identification help of soviet passive component
« Reply #8 on: January 29, 2022, 10:30:02 pm »
I would assume -1500ppm/K ?
Correct. It is ppm/C officially, but it is the same thing, of course.

-1500 is one of the worst in the series. I think the worst ones ever made were -2000.
« Last Edit: January 29, 2022, 10:40:29 pm by ataradov »
Alex
 

Online TimFox

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Re: Identification help of soviet passive component
« Reply #9 on: January 29, 2022, 10:39:10 pm »
Negative temperature co-efficient ceramic capacitors are not necessarily "bad" (although they do tend to have worse loss than NP0/C0G).  They were often used for temperature compensation in oscillators, etc., back in the day.
An example of US standard notation is "N750" for -750 ppm/K or -750/Co.
 

Offline VtileTopic starter

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Re: Identification help of soviet passive component
« Reply #10 on: January 29, 2022, 10:43:20 pm »
I would assume -1500ppm/K ?
Correct. It is ppm/C officially, but it is the same thing, of course.

-1500 is one of the worst in the series. I think they the worst ones ever made were -2000.
Yep, seems definitely something that can be found from cheap pocket radio.

Case closed finally. Thanks everyone and especially to you ataradov and Vovk_Z for details.
« Last Edit: January 30, 2022, 11:17:38 am by Vtile »
 

Online ataradov

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Re: Identification help of soviet passive component
« Reply #11 on: January 29, 2022, 10:44:05 pm »
Sure, there may be uses for them.

One cool feature of those small value tube capacitors is that you can "tune" them. If you wind a coil of wire around its body and solder one of the ends to a pin, you can increase the capacitance by a few pF. I've seen this done in amateur radio.
Alex
 

Offline VtileTopic starter

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Re: Identification help of soviet passive component
« Reply #12 on: January 29, 2022, 11:20:56 pm »
So many simultaneus responses...

TimFox thanks about note of tempco compensation, I do not work with oscillators in my electronic hobby so most of the time nanofarads are the lowest I do go.

The tuning is also interesting idea, I do wonder what kind of self oscillator it would be if wound to be a toroid over capacitor with fine enamel wire. :P

 


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