Fw: Fw: [R-390] Some thoughts on capacitor leakage

Mon, 17 Feb 2003 11:32:16 -0600

Meant R-390A, not R-390

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To: [email protected]
Date: Mon, 17 Feb 2003 11:28:57 -0600
Subject: Fw: [R-390] Some thoughts on capacitor leakage

The only other bad mica on the RF deck (with a relatively high 4.0uA 
leakage) is C286 ...also an "El Menco" 100pf mica like C327 ...mmmm,
I see a trend developing, maybe. Mfg part # CM15F101GN3.

73  Kees K5BCQ

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From: [email protected]
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Date: Mon, 17 Feb 2003 10:27:52 -0600
Subject: [R-390] Some thoughts on capacitor leakage
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Continuing on with my R-390A project...........
Time to decide which mica caps are to be replaced. Many of them "fail" at
500V in the "mica" cap position on the Heathkit IT-28 cap checker where
the eye closes at roughly 0.1uA for the "paper/mica" cap position and is
a little on the sensitive side (an Eico cap checker I had, closed at
1.5uA). So here is a better way: after determining the voltage settings
on the cap checker are "close", insert a digital uA meter in series with
the leads and read the real leakage at the WV. The C327 mica (Chuck
Rippel says it's a problem capacitor) read 2.5uA �.clearly a bad mica.
Most of the mica capacitors which closed or started to close the eye on
the IT-28, really read 0.1uA or less at 500V ...perfectly good.
73 Kees K5BCQ
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