100KW Power Amplifier

[el156]

Just for curiosity,does someone know how is made a 100Kw power amp?Things like types of tubes used,voltages involved,rectification,capacitors ,and OPTs used?I know this amps were used in transmitors modulators and still used.Would be nice to see one of this monsters.
Thanks

[wakibaki]

Water cooled tubes in the old days, and even now some are still in use.

418F 100 kW Shortwave Transmitter

Or you can get solid state:

NA100, 100 kW AM Transmitter

Just google '100kW water cooled transmitter'

w

[tomchr]

The fact that they're using a 4CX3000 running at 4 kV as a DRIVER for a 4CV100000 running on 12 kV should tell you that the warning sticker on the back of the chassis needs to be taken seriously. You know the one that says "no user serviceable parts inside"...

~Tom

[Zen Mod]

except when real serviceman is inside

[LinuksGuru]

I have schematic of 10KW and 30KW vacuum tube audio amps lying somewhere, they could make very nice 5+1 sound system. B+ voltage is just 3KW, sized like refrigerators. Indeed very nice companion to DVD player or iPod :-)

[Zen Mod]

Bereskin was very active in that field

[ChrisA]

Originally Posted by el156

Just for curiosity,does someone know how is made a 100Kw power amp?Things like types of tubes used,voltages involved,rectification,capacitors ,and OPTs used?I know this amps were used in transmitors modulators and still used.Would be nice to see one of this monsters.
Thanks

I don't think anyone has ever build a audio amp that large. Typically if you do need that kind of power they "rack and stack" quite a few 1000W class D amps and hide that in rows of racks under the stage (like for a rock band playing a open air sports stadium.

But people have built some large 100KW class radio transmitter amps with tubes. The tubes are huge, like a washing machine and have water jackets and are so expensive they are designed so they can be opened up and rebuilt after they have seen some use.
What makes it posable is that at radio frequencies the transformers can be MUCH smaller than at audio frequencies. Mostly RF amps don't need output transformers and will directly drive the antenna through some kind of resonant tank circuit

[a.wayne]

Originally Posted by Zen Mod

except when real serviceman is inside

Always picking on Jacco ......

[Zen Mod]

nope really - not this time

I just recollected my memory seeing some pictures of room sized tube xmitters , where serviceman is really walking through xmitter ...... in off state , of course

I even had opportunity to visit similar one once , even if that was size of smaller room

[metalsculptor]

Originally Posted by ChrisA

I don't think anyone has ever build a audio amp that large.

You forget AM radio, the modulator needs to be around the same power as the transmitter and it is an audio amplifier. In Australia 50Kw AM transmitters used to be commonplace so I am sure 100Kw and larger units have been built, not all AM transmitters use modulators linear mode is quite popular also.

Making the power is not difficult, high power valves are very compact compared to equivalent transistors of equivalent frequency response, I have a 4CX10000D as a mantelpiece ornament Two of them in PP will give about 30Kw with a modest 7.5Kv on the plate.
Here is one guys 12Kw RF amplifier using that valve Linear There is a more compact one on the net somewhere using 3 phase power which will fit in the boot of a car.

A 30Kw modulator would be a similar size weight is going to quite large due to the output transformer and I cannot think of any practical reason to use an amplifier this size to drive speakers multiple small amplifiers improves reliability, control and safety.

As for the techniques used, the RCA transmitting tube manual covered this a bit. PSU 3 phase full bridge choke input filter, transformer driven PP output stage, AB2 or class B. Driver stage is also PP Really it is just an upscale PP home audio amp except for the transformer coupled PP driver stage. Safety controls and instrumentation reflect the higher value of the equipment.