> 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.
** That doesnt mean it was good engineering by 1963 standards
>
> ## alpha used 1N4007's in their 374-A no tune.. pure junk. [diodes]
** Dont know of any failure issues. Later models went with the 1N5408 as the
price difference came down to almost nil.
>
>
>
>>
>> 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.
** Then you are in a very small group.
>>
>> ## 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.
** Say what?? You better get your glasses on and read an old Dahl catalog.
>> ## 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.
** Eimac didnt use ridiculous amounts of C to establish tube specs which are
usually well above the crap SS rigs in use. I can understand 330-560uF which
still may place a strenuous starting load on stock amps.
** There is a huge difference between hum from a processed AM modulator and
VOX SSB. As I keep trying to tell you show me a vintage amp that has SSB hum
problems with what you consider undersize caps. That includes your precious
Drakes.
I doubt if more than a tiny few on here gives a hoot about ESSB. Stock
linears sound fine on AM as do Class C amps with a lot less filtering than
the modulators, a single LC filter is sufficient.
>>
>> 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
** I never saw a Drake with only 210V PP drop. The iron is only .8A CCS.
Thats .4A after it is doubled which is half PEP Ip.
What does it do key up-key down?
>
> ## 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.
** I still have the 51.5UF @ 10kv Sangamo on a bottom shelf for some future
project. I believe it is over 150# but its been 20 years since I moved it. I
couldnt store wimpylytics that long (-;
>
> ## 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.
** Meanwhile most of us are grounded in the real world and happy with using
270(current Ameritron stock)-560uF during replacement time since they at
least fit existing amps.
Carl
KM1H
>
> Jim VE7RF
>
>
>
>
> Carl
> KM1H
>
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|