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Old 24th Jul 2019, 10:24 am   #1
snowman_al
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Default 510pF mica capacitor

Need a 510pF 250 volt mica capacitor to go in one of my Heathkit MA-12s.
Does any one have one something similar in their used parts box?
Alan
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Old 25th Jul 2019, 12:34 pm   #2
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Default Re: 510pF mica capacitor

I have a used Dubilier 635 series 470pF (reading 495pF) with shortish leads that you are welcome to. The 635 series is rated at 350V. I can pop it in the post if you PM me with address (no need for postage).
Otherwise Ebay currently shows the same capacitors NOS at £6 for 5.
The tolerance is +/- 20% anyway so 470pF-ish should be absolutely fine.
-Jeremy
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Old 25th Jul 2019, 12:49 pm   #3
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Default Re: 510pF mica capacitor

What's it in, the NFB loop? A few pico farads either way won't matter much as Jeremy says. I have some 560p 500v for the postage or you could use two 1n/1000p in series. If in the NFB loop you can get away with a 50v part. If set on a 510p hifi collective sell em as does this place - https://www.rush-on-line.co.uk/cap_index.php has 510p 400v = 85p.

Andy.
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Old 25th Jul 2019, 1:59 pm   #4
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Default Re: 510pF mica capacitor

I have some 510pf silvered-mica capacitors but they're quite small with a lead spacing of ~6mm and I don't know what their voltage rating is.
Tolerance is +/-5%.
Any use ?

Andy
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Old 25th Jul 2019, 2:09 pm   #5
sortedradio
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Default Re: 510pF mica capacitor

Maybe use 2 1000pf to achieve 500pF?
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Old 25th Jul 2019, 2:29 pm   #6
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Default Re: 510pF mica capacitor

500pF with 10pF 'piggybacked' in parallel would neatly do it.

These are compact Cornell-Dubilier 500V 5% from Farnell:

500pF:

https://uk.farnell.com/cornell-dubil...v-5/dp/2333486

10pF:
https://uk.farnell.com/cornell-dubil...00v/dp/2333472

Datasheet:

http://www.farnell.com/datasheets/17...449.1553868468

Hope that might help.
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Old 25th Jul 2019, 2:34 pm   #7
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Default Re: 510pF mica capacitor

I've got a few 1000pF ones too and they're a lot bigger (~21mm lead spacing) so are probably >350V dc rating.
I could send you a couple of these or the 510pF FOC if you'd like.
(They're all NOS)

Andy
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Old 25th Jul 2019, 4:08 pm   #8
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Default Re: 510pF mica capacitor

Thanks for the suggestions and offers.

It is for the EF86 phase change network across the anode load resistor, so 'sees' 120 -140 volts and is not a critical value. The one fitted is a Dubilier 635 and causes popping / rustling noises once warmed up... (It is not the EF86 or resistors, I've subbed them and is silent if disconnected.)

I was looking for something period if possible (and am a bit ocd with the look when series/paralleling values...) hence my junk box request.

I will ponder some more - Alan
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Old 25th Jul 2019, 5:44 pm   #9
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Default Re: 510pF mica capacitor

I have various 560 puff caps, but do have some nice NOS Soshin 560p if any good.

A.
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Old 25th Jul 2019, 6:29 pm   #10
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Default Re: 510pF mica capacitor

Hello,
I have some new old stock 500pf Dublier 635 mica capacitors. You are welcome to a couple free of charge if you want them.
Yours, Richard
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Old 26th Jul 2019, 11:05 am   #11
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Default Re: 510pF mica capacitor

Worth remembering that a 500pF capacitor is just -2% out of tolerance from 510pF.

Itís not as though itís a padder in a tuned circuit, so 500pF should surely do fine.
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Old 26th Jul 2019, 11:18 am   #12
snowman_al
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Default Re: 510pF mica capacitor

Thanks again everyone.
Yes 500pF is fine, and I have taken up Richard's kind offer.
Alan
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