Sent: Sunday, April 11, 2010 9:43 AM
Subject: Re: [Amps] HV lytic max V ratings..some notes.
>
>
> In a message dated 4/11/2010 9:24:56 A.M. Eastern Daylight Time,
> Jim.thom@telus.net writes:
>
> I usually sail pretty close to the wind. I work on having 1 spare
> capacitor worth of headroom in a bank. For example, if the dc voltage
> is 4500V, then I would use 11 x 450VW capacitors in the bank. Never
> had a cap go bang on me by using that crude formula.
>
>
> Denny used 7 caps when everyone else used 8. I just had to recap an
> LK-500 because of a bad cap. He always found a way to save a penny. The
> worst
> blunder I think he made was not only didn't he have a grid trip on the
> DTR-2000L, he didn't even have a metering scheme for the grid. Then when
> he
> DID use some sort of grid trip and Hi plate current trip safety measure,
> it
> was on the LK-500ZC with 3-500's. Who needs that?
> Yet the DTR-2000L is a highly sought after amplifier, and a nice one will
> bring over $1500.00. Go figure. I won't go into not using a filament
> choke
> and using chassis return on the filament supply and a blower that might
> handle a 6146.
Grid trip and metering mods for the DTR-2000L were published shortly after
it hit the market. I incorporated them in several before ready made circuit
boards became available.
Two cooling systems were used over time, a muffin fan and a small squirrel
cage blower. Using temperature sticks Ive found the blower to be more than
adequate using the stock power transformer. Directing the air flow to the
cabinet top with silicon rubber further reduces compartment temperature and
opens up room to improve the tank circuit.
Its not a bad amp, but it wasnt a good one either if you can follow my
logic.
Ive had an all stock one sitting up on a shelf for years with the idea of
doing another 6M conversion....sort of forgot about it.
If anyone wants to offer me $1500 including a full output 8877 and
completely stock, contact me off line. It has the blower. I really need to
start thinning the herd around here.
As far as the 7 caps in the LK-500 Ive been replacing them with the 475V
rated ones from Ameritron. That gives a bit over 300V headroom. Another
option, if you have or can find a cheap one, is to use a 10V or so
secondary bucking transformer with an adequate secondary current rating.
This will also reduce filament voltage to a safe level particularly if the
line voltage is high.
Amp Supply made many real good amps that are still bringing top dollar. I
cant kill my LK-500ZC that Ive had since 1986.
Since my long time friend, Bill Edwards, K4BWC, of Omega Electronics, passed
away 2 years ago Ive been handling a goodly number of those amps and helping
plug the void. I think of him and the fun times we used to have every time I
work on one.
Carl
KM1H
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