In article , tony sayer
scribeth thus
In article , John
Rumm scribeth thus
On 26/01/2021 18:33, Tim Streater wrote:
On 26 Jan 2021 at 14:55:31 GMT, John Rumm
wrote:

On 26/01/2021 11:51, Paul wrote:
Jimmy Stewart ... wrote:
On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on
the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

There are still some good-sized vacuum tubes kicking about.

https://www.nutsvolts.com/magazine/a...-for-the-21st-
century


Â*Â*Â* "The filament of this tube alone requires 23V at 500A €” thats
almost
Â*Â*Â*Â* 12 kW, or enough to power an average house."

Even their filament power is bigger than all of your
rigs put together.

And lots of copper pipe with cooling water running in it.

One of the valve based bits of kit I worked on would stick 10kW of HF
out the main feeder, and 16kW of heat out of the top vent (force fed by
blowers under a raised floor)[1]. That was a two valve stage design.
There was a solid state pre-amp, then a valve based penultimate stage to
lift to about 400W, and then a main valve to go to 10kW


[1] Don't know if the energy drawn by the blowers was included in the
vent total - I expect probably not.

Try these klystrons:

https://www6.slac.stanford.edu/virtu...ystron-gallery

rated at 75MW.

Puts those tiny 1MW radio and TV transmitters in their place! :-)



Well Klystrons are now no longer in use with the passing of analogue TV
back in 2012.

In modern UHF TV transmitters they are using a such as travelling wave
tubes solid state doesn't quite rule the roost!...

Correction!! IOT's Inductive Output Tubes !!!
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.