On Sat, 28 Aug 2004 07:38:59 -0400, Bob Engelhardt wrote:
Gary Coffman wrote:

Bob Engelhardt wrote: ...
4 PR 125A"

... about 170 watts output power. ...

Wow! This big thing will only drive a couple of light bulbs?! Thanks
goodness for transistors. Bob

Glass envelope tubes are generally much bigger than ceramic
envelope tubes of the same power rating (especially the ones
without heaters which we call transistors). That's because they
needed to keep envelope temperature below 400 degrees, but
the cathode had to be at 2300 degrees.

Back in the day, the 4-125A worked at 200 MHz when transistors
were straining to do milliwatts at 1 MHz. Of course that's all changed
now. About the only place for tubes today is when you *have* to
deal with very high voltages. Otherwise, transistors are preferred.

Gary