On 8/30/2010 12:02 PM, Rob Atkinson wrote:
> I don't have the spec. sheet right in front of me but I recall the 833
> could put out a hell of a lot of power with no forced air cooling.
> 600 w.
The 833A is a rather versatile tube with power output varying over a
wide range. Forced air cooling increases the plate dissipation from 300
to 400 watts.
> (but I forget what biasing) sticks in my mind but don't hold me
> to that. Whatever it was, it was very high and made me wonder why it
> is not used in ham amps for all these operators who are obsessed with
> not having any blower noise.
Mainly to get much power out you do need to put about 40cfm out of a 2"
outlet directed directly at the two top seals (plate and grid)
In class C a pair of tubes can put out a lot of power (2400 to 2700
watts with forced air cooling), but in class B it ain't much...(bout 225
to 250 watts with 4KV on the plate with forced air cooling and only 150
to 200 watts with convection cooling) But they are impressive and
unique looking.
If you want a convection cooled tube go with the GU81 which is As nearly
odd looking as the 833. It's over 10" tall and nearly 5" in diameter. It
*apparently* can be really abused. The Russians say the only way you
can hurt it is with a hammer. There's a schematic on the net for a pair
of them that claims 3KW out for contesting and no fan. I would assume
the mechanical construction gives each tube a lot of space.<:-))
Filament is Carbonized Thoriated Tungsten with 12.6V @ 11A
BTW they reputedly put out a good signal and they are cheap!! Sockets
run more than the tube at roughly $50 Vs $35
73
Roger (K8RI)
> My guess was supply, cost of the tube,
> and the (for hams) unconventional way they are mounted.
>
> Rob
> K5UJ
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