At 03:28 PM 4/3/2001 -0500, you wrote:
>
>My 4-1000A amp will get 1800W key down output with 4400V full load
>on the plate and 100W drive. At 5000V things start to arc all over
>the place. It is very happy with 70W drive for 1500W output and 4400V
>full load plate voltage. Tube is "new old stock", not a BC pull.
>
I had pretty much the same results with my last 4-1000 amp. The tube was
brand new, not a pull. Ep was 4800V and 100 watts drive produced 1650 -
1700 W on a Coaxial Dynamics meter; 1750 on a Bird. A Bird dummy load was
used for both measurements. The power output was originally is the 1200 to
1300 watt range - until I re-designed the input and output tanks using
W5FD's modified pi-net formulas.
Phil
>Mike, W1NR
>
>P.S. My variac is one of the BIG 240V 28A jobs.
>
>-----Original Message-----
>From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
>Behalf Of Tom Rauch
>Sent: Tuesday, April 03, 2001 2:25 PM
>To: Wynand van Wyk; Sam Belew; William Fuqua
>Cc: amps@contesting.com
>Subject: Re: [AMPS] 4-1000A Project
>
>
>
>Hi Bill,
>
>> Bill Orr stated in his article on Tetrodes used in grounded grid
>> amplifiers (about 170 watts) but at 5 or more KV it is less than 70
>
>I agree with that.....
>
>> watts for full output and about 50 for full gallon (1500 watts). Also
>
>......but that seems overly optimistic. I could NOT get 1500 watts
>out with any cathode driven 4-1000A with 100 watts of drive unless
>HV was nearly 6000 volts.
>
>A 3CX1200 has a lower driving impedance, and more gain, and
>barely makes 1500 watts at 3300 volts with 1000 watts of drive.
>
>> a 1KVA variac is small not only due to the fact that the plate input
>> power for 1500watts output CW would be over 2KW but that the current
>> drawn by the power supply is many times the RMS value for a Capacitive
>> input filter. Not so much a problem with a inductive input filter.
>
>Yep, I'd use that 1kva variac for a filament supply. It's too small for
>an anode supply even in a 500 watt output PA.
>73, Tom W8JI
>W8JI@contesting.com
>
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