10-01-2026, 03:39 PM
Hi Harry,
The mica sheet in the adjustable capacitor we often find after 80+ years gets dirty, the dirt collects moisture and causes all sorts of problems. It is removable and can be cleaned. Just remove the adjustment screw and the mica should be loose and can be coaxed out of the metallic sandwich. Be very gentle, they are delicate. Occasionally you will find one that has a crease someone else has damaged during removal. Place the mica on a flat, clean surface and soak it with alcohol, then gently wipe it clean. Use a brush soaked with alcohol to clean the capacitor, then put it back together. One of the plates is spring loaded so don't be too aggressive on the cleaning.
The mica sheet in the adjustable capacitor we often find after 80+ years gets dirty, the dirt collects moisture and causes all sorts of problems. It is removable and can be cleaned. Just remove the adjustment screw and the mica should be loose and can be coaxed out of the metallic sandwich. Be very gentle, they are delicate. Occasionally you will find one that has a crease someone else has damaged during removal. Place the mica on a flat, clean surface and soak it with alcohol, then gently wipe it clean. Use a brush soaked with alcohol to clean the capacitor, then put it back together. One of the plates is spring loaded so don't be too aggressive on the cleaning.
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