Renewing the 70E8 Dessicant Capsule
Paul Courson, WA3VJB
The dessicant capsule on the 70E8 PTO can be "renewed" in the kitchen oven. Pre-heat the oven to around 250 degrees (not critical), and put the capsule on a cookie sheet, letting it bake on the shelf farthest from the oven's heating element for perhaps an hour. You will see that the crystals turn blue again. Save this process until you are ready to reassemble the PTO with the tube shield, all screws, and glyptal cement so that it is hermetically sealed. The best time to do this is when the humidity in your home is low, and you won't collect much moisture in the walk from the kitchen to the workbench. (Wintertime in most climates.)
I have found that the modular connector (4-pin) is a point of entry for moisture. You can seal that with a light bead of RTV, letting it dry before re-assembly and re-installation. The bead, placed around the bakelite rectangle holding the pins of the PTO connection, is easily peeled off if you need authenticity for a show. You could also use RTV around the base of dessicant capsule and to seal the tube shield and its mounting screws. I find it more serviceable than gyptal, which is brittle and tends to need digging out from the phillips-type screw heads.
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11 Feb 1997