QROKING@aol.com QROKING@aol.com
Sun, 16 Mar 1997 10:39:47 -0500 (EST)

I read with great respect the suggestion of W8JI to, I think examine,
perhaps, the quality of componets that Hakan and I have used in our power
supplies.  Hakan and I seem to be suffering from the same "REAL" problem.  I
will run down the componets I am using in mine, and I am sure Hakan will do
the same.  I am using a brand new 240/3000 volt transformer from Peter
Dahl...cost $500.00.  The rating on it is 2 AMPS CCS.  I purposely did this
purchase to avoid the ultimate problem I am having.  I am using new W2AU
silicon alley brick diodes...$60.00.  I have experimented with different
capacitor values and types.  Firstly I used 10 computer grade electrolitics
in series value of 1200uf @ 450.  This gave me 120uf total.  The only other
thing left is the bledder resistors, they are ceramic and about 200k as I
recall.   This set-up still gave me a HV drop of nearly 900 volts of the
no-load DC.  I consulted Bill Orrs book on power supplies and his chart
indicated that 80uf was needed to yield about a 5% voltage regulation.  What
happen?  Ok, then I tried a different capacitor set up.  This time I used 2
  32uf  military type oil filleds in parallel @ 4500, this gave me 64uf.  I
fired the supply up once again and again 900 volt sag, no difference.  I then
thought about Bills magic number of 80uf, I surely was skeptical that another
15uf would make a difference, but anyway I added another 32uf in parallel
with the 64 and still the same.  It was said that properly designed capacitor
input filter should have at least 10% regulation.  So if my regulation is no
where  near this figure, where is my design error?  As I mentioned before, my
line voltage at the transformer input under a 45 amp "key down" load only
goes from 238 volts to 229 volts.  This is well within electrical specs.  Now
most of what I have been hearing is theroy, but what happens in REAL world?
  ESR of the plate transformer? Dont know..but I dont think I can wind a
transformer any better than Mr. Dahl.  What gives?   LOU

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