> [Steve Katz] The cheap 4.2kV (yellow) ones are classified as
> non-hydroscopic mica-filled phenolic; the more expensive 7.2kV (red and
> black) one are classified as non-hydroscopic linked polytetraolefin (PTO), I
> believe...
Absolutely stay away from the lesser-rated Millen connectors in any HV
application. The first-generation Alpha amplifiers used
these connectors between the P.S. compartment and the R.F. deck. Even with new
connectors and 4 KV applied, all bets are off. I
recall trying to localize a HV glitch problem in one of these amps and after
unsuccessfully trying everything else, I decided to
bring-up the amp at low voltage (2.6 KV) with the top cover off and
subsequently noted a blue corona around the connector. I
ditched the Millen connector in favor of a glazed-porcelain feedthrough and
have never experienced a single problem since. Later
Alpha amplifiers simply passed the silicone HV wire through a chassis hole and
rubber grommet. This solved the flashover problem,
but made servicing difficult. It's a shame that these connectors were
manufactured by Millen: Every other item in their extensive
product line was designed and produced to perfection.
-Paul, W9AC
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