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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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28th Nov 2022, 9:59 pm | #1 |
Pentode
Join Date: Feb 2020
Location: Waterlooville, Hampshire, UK.
Posts: 201
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Sticky LEM Silver Mica caps
I've replaced a few waxies on my latest project, but was wondering how reliable the above are.
They are not quite waxy, more 'sticky'. The first one I checked was fine, but I'd welcome any views - they're not too easy to get at!
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Pete BVWS Member |
28th Nov 2022, 11:32 pm | #2 |
Octode
Join Date: May 2003
Location: Belper Derbyshire
Posts: 1,936
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Re: Sticky LEM Silver Mica caps
I think they will be fine. The outside of them is a bit sticky and covered in dust, though as long as they are not disturbed mechanically, silvered mica type capacitors are usually very reliable.
Christopher Capener
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Interests in the collection and restoration of Tefifon players and 405 line television |
30th Nov 2022, 4:53 pm | #3 |
Pentode
Join Date: Feb 2020
Location: Waterlooville, Hampshire, UK.
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Re: Sticky LEM Silver Mica caps
That helps put my mind at rest. Thanks Christopher.
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Pete BVWS Member |
30th Nov 2022, 7:34 pm | #4 |
Dekatron
Join Date: Nov 2010
Location: Oxford, UK.
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Re: Sticky LEM Silver Mica caps
I'm looking at some NOS LEMCO 1500pF +/-5% mica on my desk as I type. Exactly the same as in your set, wax coated.
They measure just fine - well within tolerance, and low loss on my bridges (note the plural!) So I would say you have nothing to much to worry about with them in your set. Craig
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30th Nov 2022, 7:36 pm | #5 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,820
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Re: Sticky LEM Silver Mica caps
I’ve normally found them to be reliable, but a few years ago I was restoring an Ekco A22 and I found both of the 2 on that chassis to be faulty, but that chassis had been subjected to severe damp at some point, possibly even submerged!
Regards Lloyd |
30th Nov 2022, 8:20 pm | #6 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
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Re: Sticky LEM Silver Mica caps
Just a question on these style of mica's, does the size of them relate to the operating voltage?
Adrian |
3rd Dec 2022, 9:56 am | #7 |
Nonode
Join Date: Mar 2010
Location: Dukinfield, Cheshire, UK.
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Re: Sticky LEM Silver Mica caps
I suppose so. To withstand higher voltages the plates have to be spaced further apart, leading to lower capacitance. To make up for this we need more plates (a thicker capacitor) or bigger plates (bigger area).
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Andy G1HBE. |
3rd Dec 2022, 10:11 am | #8 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,573
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Re: Sticky LEM Silver Mica caps
I have a box of caps in different sizes, no longer any writing on them that can be seen, I can determine their capacitance but not voltage rating?
Adrian |