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Old 28th September 2009, 06:59 AM   #1
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Default The DeForest 504 tube

I have a couple of DeForest tubes I cant find any info on. They are in great shape. They look new in fact. The problem is I don't have any data on them.
They have the word DeForest and 504-A written on the base of them. They are about 14 inches tall. If I am right, as I recall the anode cap is on top and the grid is on the side with a metal cap as well. Any info would be appreciated. I have been looking for a long time. I would say they have at least a 500 watt dissipation rating. That of course is just my visual and I don't have proof. I am thinking an old broadcast transmitter tube.
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Old 28th September 2009, 08:27 AM   #2
Glowbug is offline Glowbug  United States
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Lee De Forest was the inventor of the's odd, Googling doesn't find much, I tried looking through QRZ's forum (a ham radio site) too. I have no idea if these links are valid or not, but if nobody else can help you, these guys probably can:

Whatever it is, it probably hasn't been in common use for a long time.
The machine does not isolate us from the great problems of nature but plunges us more deeply into them. - Antoine de Saint-Exupéry
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Old 28th September 2009, 04:06 PM   #3
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Thanks, I sent them an email to see what happens. here is what it kinda looks like. I guess I need to get a pic of them.

Last edited by yourownfree; 28th September 2009 at 04:16 PM.
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Old 10th February 2014, 06:32 AM   #4
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Default here is a pic of the tube from the tube collectors site

here is the pic
Its the one on the right in the picture. It stands about 12 inches. I dont recall getting an email back from them. It has been while since I looked at them. I was thinking about using them in an amplifier project, but since these might be one of the only ones left in the world I am not sure if I want to do that. besides I would have to have sockets made for them I suppose. I would be interested in knowing what the specs are. Plate voltages and plate dissipation. Even an internal diagram triode I suppose being that old. I will go through some early 1900 radio magazines and see if I can find anything.
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Old 10th February 2014, 08:34 AM   #5
Ceglar is offline Ceglar  Australia
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museum piece.

what you do with that is indeed a question.

wait… … ..

Last edited by Ceglar; 10th February 2014 at 08:42 AM.
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Old 10th February 2014, 08:40 AM   #6
Ceglar is offline Ceglar  Australia
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otherwise, I can always swap it with you for a Mullard 12AX7 :-)
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Old 11th February 2014, 03:58 PM   #7
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Yeah a museum piece. I will make a display case and put them in for show. I might even check filament and light them up with minimal power just to watch them glow. I bet with a 1,000 volts on the plate one of us will get some action, the tube or myself if I touch it. I wouldn't build an amplifier around these and then find out they dont work or worse yet it works for 1 minute and filament burns out. I will stick to something I can replace. I'll pass on the 12ax7 tube.
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