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vacume caps

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p.larner:
are vacume caps more efficient than fixed silver mica?.

tggzzz:

--- Quote from: p.larner on March 20, 2024, 11:58:33 am ---are vacume caps more efficient than fixed silver mica?.

--- End quote ---

No, but airegapd caps are better than plystyureene caps.

TimFox:
It's not hard to find real data about vacuum capacitors, which are available at very high prices either fixed or variable capacitance.
Seek and ye shall find:
https://library.e.abb.com/public/bea07f06039c4a3685bec40a01ac1122/7TKK000115_Jennings_vacuum%20devices_catalog_US.pdf?x-sign=Yi7I0LOgcp0EKk14PWLn0g+EnDe3c/37jNeSjN1jKFU1Dx8kse+gnzGmfTjRrPA6
The main reason to use them is their huge RF current ratings, along with high voltage ratings.
Jennings does not specify Q or loss, stating that the loss is generally negligible:  as a dielectric, vacuum itself has no loss mechanisms until you get to the huge E fields required for quantum behavior such as vacuum polarization.
If your application requires huge RF current or voltage ratings, fixed-value mica capacitors (not silver-mica) are available, useful up to around 3 MHz.
At 1 MHz, Q is good, about 2,000.
https://www.cde.com/resources/catalogs/HVOLT-CYL.pdf

vk4ffab:

--- Quote from: p.larner on March 20, 2024, 11:58:33 am ---are vacume caps more efficient than fixed silver mica?.

--- End quote ---

In what context? You are comparing 2 capacitor types that have very different use cases.

p.larner:
The context is for use in an l match atu.

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