I've had vibration experiences with several Drake power supplies and have found the following causes. Whether they appy in this instance, I can't say.
1. Critical proximity between a metal case and the transformer, such as with an L4/L4B/L7 supply. A piece of stiff foam rubber cured the problem. 2. Loose transformer laminations and/or windings. Not very common. Through-bolts for the transformer laminations should be tight. A loose winding usually caused noise but little vibration. Some flowable RTV (the kind used to seal windshields and acquariums) oozed into the top of the windings, set to dry, then the same from the bottom; works only if loose windings are near the exposed areas and not hidden. 3. Excessive load on the power supply and/or a capacitor developing lowering internal resistance. Usually a problem only if an over-rated fuse has mistakenly been inserted. Proper size fuze should be used, capacitor checked or replaced, and load current tested. I'm sure there are other causes, these are just the ones I've found to be most common in my personal experiences. 73, Evan
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