[AMPS] 4-1000A Project

[Tom Rauch]

> Sam, can you put your hands on a VARIAC @ 1000VA (10A).
> 
> I use Variacs on all my home built power supplies.  That will give you
> 100V up to whatever you can get out of the supply.

I avoid variacs because they reduce dynamic regulation of the 
supply. 
 
> In my experience you need minimum 2700 Volts (100 watts driving) up to
> maximum of 3500 Volts ( 60 watts driving) in grounded grid with
> 4-1000A.
> That should give 2 kilowatt PEP.

I've never found that! The 4-1000A was an impressive tube in 1955 
or 1960, but it is anemic by today's standards.

Even with anode voltages of 5500 volts, I generally saw only 1200 
watts or so output with 100 watts of drive.

The power gain of a cathode driven, for the most part, is related to 
the ratio of driving impedance to anode impedance. Since the 4-
1000A has a cathode impedance of over 100 ohms, gain is very 
low. 

Gain is much lower than a 3-1000Z or a 3CX1200, let alone a tube 
like a 3CX1500A7.

I'm sure your power figures are not correct....but even if they are he 
is talking about grid driven service. In that case I would follow the 
manufacturer's suggested parameters.


73, Tom W8JI
W8JI@contesting.com 

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