Specs for EL84 amp.....JC's advice needed.

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Jonas Gemini
Hey get your own solder
Posts: 292
(2/6/04 7:49 pm)
 Specs for EL84 amp.....JC's advice needed.
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 Jeff,

Using the 270EX (i think) How does your spitfire clone spec out? What is your EL84 plate voltage and cathode voltage and power tube cathode setup?

The schematic calls for 285 -0- 285 tranny which, according to the schematic, puts about 350V on the plates. By doing the math, it looks like the spitfire runs hot.

Jonas
 
jc
I only work on Fender's
Posts: 673
(2/6/04 10:27 pm)
 Re: Specs for EL84 amp.....JC's advice needed.
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 Jonas,
I have used a 270DX and 270FX for spitfire/lightning clones. I normally use EL84M's. I have run some stock sovtek el84 in them but not for extended lengths of time.
These voltages are with a 5AR4.

When I use the 270FX I get a plate voltage of 368v and 13v with a 150 ohm cathode resistor.

When I use the 270DX I get a plate voltage of 356v and 13v with a 150 ohm cathode resistor. This is probably pushing the limits of this transformer but it handles it fine. I have played through this for hours and I can still wrap my hand around the PT.


 
 
Jonas Gemini
Hey get your own solder
Posts: 293
(2/6/04 11:15 pm)
 Re: Specs for EL84 amp.....JC's advice needed.
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 Thanks JC

Thanks for the information. It looks like your amp runs hot but is still good to go. That's good. I got a little worried when I did the math a while ago. Yes the EL84M is the equilivant to the 7189. It is the same tube as the EL34/6BQ5, but it has a maximum plate voltage of 400V so I will be good to go there. I will give it a try and see what is going on. I will let you know. I think I have some 7189's laying around.

Jonas
 
 
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