Look - you DON'T have to spend $14,999 for a hi-fi!

[whirlcool]

The set my uncle had and most of the ones shown in this thread are solid state. It didn't sound as good as GE's tube amps did. It had a cheap sound to it. I thought that Zenith or Magnavox consoles sounded much better.

 

[tolivac]

The SE amp does make a good low level modulator for that transmitter.Now if we could package that as a Hi-Fi Amp-the audiophools would go bananas!Yes--we are using 845 tubes in them from a Hi-Fi supplier-only source now-or the one that gave the best bid.The GE 250Kw transmitter use a direct coupled PP modulator stage using 7482 vapor cooled triodes-same tube as in the RF driver and RF power amps.Now-if some audiophool would like to use the 7482 tube as a SE amp-they are welcome to try!!!The tube weighs in at over 200Lb,needs a boiler for the anode,and a 15Kv power supply.The 5682 and 5681 tubes in the CEMCO Doherty are forced water cooled threu the water jacketed plate connection.These tubes are unique for their power rating--they weigh only 60Lb so a crane tube puller isn't required.The stage uses a total of 4 of them-PP-2 in the Carrier stage-another two in the peak.A 5681 PP stage drives the carrier and Peak stages.The 845 modulator modulates the grid bias for these.One of any of these tubes now cost under 15K if you buy them as rebuilt.The quality of them is sort of poor-esp the 5681,82-the 7482 tubes are OK.Both came from Machlett labs-then Machlett was bought up by Eimac.

 

[cuffs054]

Tol, can you post any pics of those tubes? The whole setup sounds fascinating!

 

[tolivac]

I have some pictures and videos-but can't link them to this computer.In the meantime Look up Jim Hawkins Radio World.He is a "Ham" type person that has taken many "picture" tours of various transmitter plants.Google that and you should find it.Then on his website he has a "VOA Tour" thats it.He has many picures of the plant.YouTube has many,too.There is a video tour of VOA "A" plant that was closed in 2006.B plant where I am at is still operating and will continue to do so.The A site equipment is largely the same as B.I have worked in all three Greenville plants.The only diffrence in A plant was two transmitters that were Continental Electronics 420B and a Marconi-forget the mod#.Sadly the transmitters at the A plant are now hanger queens and scrap metal at this point-will never play again-too many parts taken from them to keep B plant rigs operating.The A plant is going to be turned over to the state of NC in the upcoming future-they have plans of using it as a campsite or a solar power farm.The antennas will have to come down.Sort of sad.Miss that place-worked there for about a year.B plant is the only remaining SW Gov't broadcast facility remaining in the US.