7 kW output. Assuming 60% efficiency, that would be 7000 divided by .6,
then divided by 240, or ~50 amps Hafta run AWG 6 service entrance cable
with a 60 amp 240V breaker to the ham shack for that. Add air conditioning
too. And get ready for blinking light complaints from any unlucky close
neighbors. That's like a charging circuit for a Tesla. 😁

73, Guy K2AV

On Mon, Jun 22, 2026 at 2:30 PM Wes <[email protected]> wrote:

> Well, that should certainly help you make "Honor" Roll.
>
> Wes  N7WS
>
> On 6/22/2026 5:15 AM, jim.thom jim.thom--- via Topband wrote:
> > Buddy back east, asked me to post this for him.  If interested, contact
> > Roger,  VE3ZI.   He is moving back to the UK, and does not want to ship
> it
> > to the UK.
> >
> > "The amp uses a 4CX5000A which was new old stock and has very few hours
> on
> > it. It is driven in passive grid and has a GM3SEK tetrode board
> > considerably modified for the high screen voltage. The plate tuning
> > capacitor is a 15kV 60A type and the output capacitor is air spaced.
> There
> > are vacuum relays on both input and output. There is a Heyboer CCS 4500V
> 2A
> > transformer. This provides something over 5kV on load - would be a bit
> more
> > but my mains supply sags. There are separate meters for grid current,
> > screen current, filament voltage, plate voltage, plate current and
> relative
> > power output. According to my LP100 power meter it will provide 5kW
> > continuously and 7kW if pushed. It is cooled by a 8" blade diameter fan
> and
> > stays nice and cool. There are separate controls for bias and filament
> > voltage adjustment, and filament, screen and plate voltages are step
> > started. It is normally run in Class AB1, but bias can be adjusted for
> > Class C if preferred."
> >
> > It can also be easily modified to add  80 and 40m if you wanted to.
> > Roger can provide pix, schematics, etc.
> >
> > Contact info.
> > email: [email protected]
> > Cell: 705 988 0880
> > Address: 2728 Eden Township Road, Sudbury, OM, P3G 1M1
> >
> > 73 Roger  Parson's, VE3ZI
> > _________________
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
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