Replacing Filter Capacitors on the Drake R-4B

Quad filter capacitors are scarce or no longer available, and the available space below the R-4B chassis rules out using four single capacitors.

I installed four singles on a 5-pin plug in the place of the quad unit, however (see drawings, below), and it worked out just fine! A socket was installed in the old chassis hole and wired to connect to the replacement capacitors.

Then, wire the individual capacitors to a mating 5-pin plug and you have a four-section filter capacitor.

Older-style plugs and sockets like the 5-pin unit I used (or other pin configurations, such as octal) often are available very inexpensively at hamfest flea markets.

The ground plate on the plug–used as the common or negative capacitor terminal was cut out using the outline of the old capacitor mounting plate.

A locking ring holds the plate in place. While I installed my unit in a Drake R-4B, this idea is applicable to any older gear that calls for a multiple-section filter capacitor can.