On Tue, 2008-12-30 at 14:24 -0600, Roger Hughes wrote:
> HI Gerald. Old heathkit SB23b.
SB23B won't do 1500 volts, nor 3/4 amp. Nor will the SB-200 power
supply.
> I can't remember model. for transformer. Also
> the SB-200 heath amp can be easily converted to 6m Amp. My friend did one,
> but I have no idea. He got the mod off the web.Each one if those should be
> cheap. They may be worth a check. 73 Roger.
Not when I have a box with three good 4CX250B in parallel for 6m. I
don't need a power supply, Jeff does, and he also has the final built
already.
Also three grid driven 4CX250B take only 10 watts of drive, while the
converted SB-200 would take at least 100 watts (because its grounded
grid instead of a gang of grid driven tetrodes). And probably won't put
out the 1150 watts key down that the three 4CX250Bs will.
73, Jerry, K0CQ
> ----- Original Message -----
> From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
> To: <tentec@contesting.com>
> Sent: Tuesday, December 23, 2008 12:17 PM
> Subject: Re: [TenTec] Transformer and schematic help needed
>
>
> > On Tue, 2008-12-23 at 09:05 -0800, Jeff wrote:
> >>
> >> Wanted Transformer close to 1500V @.750Ma
> >>
> >> Hello Folks I am looking for a transformer that is 120 volt primary and
> >> around 1500 volts on secondary with at least .750Ma rating. I do not want
> >> any microwave oven transformer’s… Also don’t want any expensive PW Dahl
> >> type I simply can not afford them although I wish I could. I am retired
> >> and on fixed income and I am trying my best to make home brew 6 meter
> >> amp running a trio of 4CX250B tube’s And all I need is now to make the
> >> power supply. Any help would be most appreciated.
> >>
> >> Any one having great schematics they would send of a power supply would
> >> be great to.
> >> Many thanks and Merry Christmas to all. Jeff
> >>
> >
> > So you wish a DC supply that puts out about 2 KV at 3/4 amp DC? That's a
> > lot of power on a 120 volt line, especially figuring the line current
> > waveform won't be nice, but will be peaked from the capacitor input
> > filter.
> >
> > Look for something like a Dentron MLA-2000 or 2500. It ran a pair of
> > 8121 at about that voltage and current. New PA tubes are a serious
> > expense so a used amp needing tubes tends to sell fairly cheaply.
> >
> > Look for a collection of control transformers with 600 volt and 480/240
> > primaries. Run them backwards with the primaries in series to get 750 or
> > so volts for a voltage doubler. What you save in transformers though
> > will be eaten up in filter capacitors.
> >
> > Last I heard Dahl was retiring due to health problems and closing the
> > business so that source may be totally gone, except used.
> >
> > 73, Jerry, K0CQ
> >
> >
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