[JMS] Millen 90281 HV Supply

[Paul Christensen]

A follow up to my progress reported below.  I've now gone through two sets
of old GE Pyranol oil caps that are on the input to a dual Pi filter.  I
don't know if the caps are just old and failing.  Or more likely, the caps
are on the ragged edge since Millen specified 1KV caps at the filter input
of a dual C-L-C Pi network.  In each case, the caps fail shorted.  The RMS
voltage is just over 1KV with a high input peak voltage.  What I'm thinking
is that my line voltage runs 127V and normal line voltage in the early 1950s
was probably closer to 115V.  So, I've ordered a new set of German oil caps
and will only operate it with a Variac to pull down the line voltage.
Someone help me remember -- are oil caps rated for WVDC or peak voltage?

The 90281 has a jumper to bypass the problematic input caps, leaving a choke
input.  Sure, I can leave it this way, but it would be nice to have a
reliable supply that works as designed.  Anyone have thoughts as to the
repeated Pyranol cap failures?  The oil caps further downstream are fine so
far and are probably helped with a lower peak voltage.  

Paul, W9AC

-----Original Message-----
From: Paul Christensen [mailto:w9ac at arrl.net] 
Sent: Wednesday, May 11, 2016 7:12 PM
To: 'james_millen_society at mailman.qth.net'
<james_millen_society at mailman.qth.net>
Subject: Wanted: Millen 90881 Band Coils

Looking for 160m through 20m coil sets for the 90881 500W Millen amp.  I
know they're scarce but please keep me in mind if you have, or find extra
coil sets.  I already have the 10m set.  

Two weeks ago, I refinished the front panels on Millen 90281 HV and Lambda
Model 28 power supplies.  I followed the instructions on the VHT wrinkle
paint can and would you believe it turned out like a factory job?  When the
XYL was out, I used the kitchen oven and set it to 160 degs.  Applied heat
for 15 minutes and the job was done.  

I did depart from the instructions with the application of a light gray
primer after extensive sanding.  Application of the primer was worrisome but
with three heavy coats of VHT, the paint still builds into a consistent
black wrinkle finish.  I had previously encountered paint flaking on some
old gear that wasn't primed.   So, pretty happy it turned out okay.

I'll post links to photos on my QRZ.com page when it's all racked up.

Paul, W9AC