[Amps] 4-5000 and others

[Manfred Mornhinweg]

As usual, I come a bit late with my comment:

I have no idea whether a 4-5000 existed, but I know for certain that big 
air-cooled tubes did exist.

The Radio Club Concepcion, here in Chile, where I did my first steps in 
ham radio at age 13, had a nice display with some transmitting tubes. 
There were the typical 3-500Z, 813, 4-400, and others, and there were 
also some high power tubes of power leves far above the ham limit. These 
were all air-cooled glass tubes. The largest of them was easily 50 or 
60cm tall, and maybe 15cm diameter, or a bit more. I remember an inside 
structure much like a 3-500Z, with a finned anode, but of course much 
taller.

I have no idea what type number this tube had, nor do I know whether 
this was an American or European tube. But I was told that it was a pull 
from a local 10kW AM broadcast station, that started operation sometime 
in the 1930's.

Given its size, it seems plausible that this tube ran the 10kW all by 
itself. In strongly driven class C that means probably no more than 2kW 
dissipation, at most 3kW, which must have been reasonably comfortable 
for this big bottle, sitting in the airstream of a fan.

Manfred


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