Date: Tue, 13 Apr 2010 10:25:58 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] HV lytic max V ratings..some notes
The L4PS.. and L7PS used 100 k , 2 watt carbons... and even they look
> new after 30+ yrs.
** Dentron did the same. Alpha used a pair of 220K in parallel.
## Drake was using 100k 2 watt in the original L4PS.. back in 1963.
## alpha used 1N4007's in their 374-A no tune.. pure junk. [diodes]
>
> 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
> isn't capable of more and its the same with many price conscious amps.
### I can hear the diff with ESSB. I can also hear the diff on AM. I'm not
talking abt 120 hz ripple either. The ESSB audio sounds cleaner.. as does
AM audio. I haven't tried FM..yet.
>
> ## 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.
** Im talking about commercial ham amps. Anyone can go oversize on HB with a
credit card.
### say what? The alpha's all have a 3.5 kva CCS xfmr... and so does the
AL-182/1200/1500. So does the ten tec centurion.
>
> ## 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.
** As well it should go up. Its no different than the vintage requirement
for a stiff L-C-L-C filter in a modulator PS plus with a stiff bleeder. You
barely see the HV meter move.
## so what's wrong with big C filters then? You can buy surplus big 2300uf +
caps for the same price as new 330uf to 560 uf vcaps. An extra free
100-200 w pep out and better imd, is nothing to sneeze at.
>
>
>
> 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.
** Serious overkill unless you can measure an improvement that is actually
audible. Otherwise it is just bragging material.
## the 2500 uf caps were dirt cheap, surplus. I can A-B between
a stock 25 uf L4B.. and a 2nd L4B.. with 312 uf filter in it.... big
difference. I run the 2x L4B's nose to tail, tuned up on same freq.
A rotary switch ensures only one amp's key line is active at any one time.
Dunno what it is, but it cleans up the audio.
## P-P voltage drops from 210 V.... down to just 16.8 V P-P
## watching that array solutions wattmeter, last few led segments,
dithering away, drove me nuts... same deal on the RF scope. That
was with a CXR.. and anything from 700-1300 w out. [stock - 25 uf]
>
> ## 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.
** There is something seriously wrong with that 800V drop.
## agreed. An alpha also uses the same 12 ga wire...and minimal
problems. The 46 lb mag cap will have to be tested with the 2 ga wire,
and only then, will we know if the mag cap is the problem.
Im convinced that real filter rated oil caps give better regulation.
## I have 4 x 47.6 uf @ 4500 vdc Oil caps.. [ came from henry radio yrs
ago]
made by CDE. These are real deal TX caps.. not energy discharge junk. I can
put
them all in parallel 1-2-3-4 at a time.. or series /parallel em for 23.8 uf @
9 kv
and also 47.6 uf @ 9 kv. 12" tall x 8" wide x 4" deep..30 lbs, welded
steel cases.
They don't hold a candle to the big electrolytics. I can run the oil caps by
themselves,
or parallel em with high C lytics... or run just the high C lytics. The
weight diff
alone is massive. 120 lbs for 4 x oil caps [47.6uf @ 9 kv] vs 17.5 lbs
for 125 uf
@ 9 kv for 20 x 2500uf @ 450 vdc lytics.
## trying to compare 200 uf caps with their 1 ohm ESR VS .017ohm ESR modern
caps
is like apples and oranges. They were cheap , surplus, so I took advantage
of that,
to run the various experiments.
Jim VE7RF
Carl
KM1H
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|