[Amps] (1) bleeder resistors - suggestion to leave them out; (2) thoriated filaments in "drilled-by-Customs" tubes; (3) oxygen-free terminals

[Gene May]

(1) I think this would be a BAD idea.  Some time ago, I bought a bunch of electrolytic caps to be used in a 3 KV plate power supply.  Out of curiosity, I put some DC across them for a couple of hours and then tested their leakage resistance.  There was a BIG difference, well over a 20:1 ratio.  If they had been put in series without bleeder resistances low enough to "swamp" the leakages, the voltage drops across the least leaky in the power supply would have exceeded their ratings by a considerable amount.  Wishing to reduce wasted current, I considered putting bleeders across each that would be "tailored" to their leakage.  After further testing, I saw that they each "aged" at a different rate, so after a while, some were significantly leakier than others and the voltage drops across each began to diverge significantly, and I could not depend on the voltage drops staying under their ratings.  So much for that idea.  Use bleeders.
 
(2) These tubes appeared to have indirectly-heated cathodes.  Thorium is put on the surface of cathodes of tubes (like 3-500Z's and 4-400Z's, also on consumable electric welding rods) whose filaments are  the cathodes; it increases the filaments' electron emission significantly.  It would be without function on indirectly-heated tubes, and is very unlikely to be put on their filaments.
 
(3) Some persons in the "golden ear" high fidelity fraternity claim to be able to hear differences between "plain ordinary" copper wire and "oxygen free high conductivity" copper wire.  No comment on that.  Assuming that there might be some advantage to such terminals (?!?!?!), I have, ah, further doubts about whether such a pristine condition would be maintained after one soldered something to them.  My guess is that the author of the ad for those glorious terminals hadn't the least idea of what he was talking about, and threw it in as hype.
 
Gene May
WB8WKU