Date: Mon, 12 Apr 2010 10:17:32 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] HV lytic max V ratings..some notes
I dont see anything wrong with a 5-10% variation in the voltage across each
cap in an amp with enough headroom. Individual capacity was all over the
place 25-50 years ago unlike today where 20% is the normal spec.
As some equalizing resistors do age it is always an increase and rather
uniform in my experience with the non carbon variety.....thats a reduction
in heat when they go from 50K to 65-70K as in the NCL-2000 for instance.
The 30K Heaths rarely budge.
### 30 k ohms is way too low a value. All as you are doing is cooking the
caps. The L4PS.. and L7PS used 100 k , 2 watt carbons... and even they look
new after 30+ yrs. I put the new 1% tol vishay's in there.. and there is
variation at all between caps.
I still say that going extreme in filter C is a waste of time in most off
the shelf amps. Ive yet to hear any audible ripple complaints about 80-150uF
caps used in strings in the old days. Going from 200 to 330uf as I do with
SB-220 repairs makes only a very slight PEP improvement; the transformer
isnt capable of more and its the same with many price conscious amps.
## The SB-220 xfmr is only a 500 VA unit... which is fubar. Big diff between
a 500 va xfmr and a 3.5 kva xfmr.
## putting 600uf caps in a AL-1500 does make an improvement. You
can get em in 500 vdc too. Pep out is up. I'm convinced imd is improved.
Now if you want to run strings of 2400-4700uF caps with your 253# Dahl iron
on a 3x10 or whatever that is your business.
## I used 8 x 2500 uf caps on the L4PS.. and B+ doesn't budge on ssb.
## The single GS35B 6m amp,..used the 46 lb mag cap xfmr... and B+ dropped
800 vdc. There was also a 6 vac drop in the 12 ga wire. The 2 x GS35B 6m amp
uses 2 ga wire and a bigger xfmr... and a string of 3900 uf caps. V drop is
only 150 vdc
power output is quadruple.
Later.. Jim VE7RF
Carl
KM1H
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