[JMS] Millen 90281 HV Supply

[Brian Harris]

Paul,

It has always been my understanding that all capacitors are rated at wvdc unless otherwise specified. I will be sure to keep the line voltage at 115 or less when I get around to firing up my 90281.  From your tip, I will also check the caps on mine before applying power.  

Brian

Sent from my iPhone

> On May 24, 2016, at 6:59 AM, Paul Christensen <w9ac at arrl.net> wrote:
> 
> 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
> 
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