[Amps] Fiament watts

[Roger]

On 8/28/2010 10:10 PM, donroden at hiwaay.net wrote:
> Which of the 3K / 5K tubes have the LEAST filament watts ?
Figures are taken from Eimac data sheets.  There are quite a few tubes 
in the 3000 to 5000 watt dissipation range but I believe these are the 
most popular and common.

3CX5000A7 10.0V @17.5A  175     Watts Oxide Coated Unipotential   (5 min 
warm up)
YC156            15V    @  15A   225     Watts Oxide Coated 
Unipotential  (6 min warm up)
4CX3000A7  9.0V @ 41.5A  373.5 Watts Thoriated Tungsten   (Instant on 
but need soft start on filament)
3CX3000A7  7.5V @ 51.5A  386.5 Watts Thoriated Tungsten   (Instant on 
but need soft start on filament)
4CX5000A     7.5V  @   75A  562.5  Watts Thoriated Tungsten  (Instant on 
but need soft start on filament)
4CX5000R     7.5V  @   75A  562.5  Watts Thoriated Tungsten  (Instant on 
but need soft start on filament)

By comparrison:
The following tube pairs can run about 4,000 to 4500watts nominal output 
and possibly 5KW PEP compared to a bit over 5 KW nominal for the  3CX 
and 4CX3000 series.
IIRC all are 3 min warm up.
A pair of 4CX1500Bs         6.0V @ 20A = 120 Watts (6.0V at 10A each)
Although the FU728F is rated at 1200 watts plate dissipation I've found 
they actually will run a bit more output than the 4CX1500B
A pair of Chinese FU728Fs  9V @ 17A = 153 Watts (8.5A each)
NOTE the FU728F is basically interchangeable with the 4CX1500B with the 
exception of the filament voltage and centering pin diameter.
A pair of 8877s                    5.0V @ 20A = 100 Watts (10A each)
3CPX1500A7s (same as 8877 but can run more voltage on the plate)


> Don WA4NPL
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