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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

6240G Data Sheet

I was wondering if anyone has a data sheet for a 6240G vacuum tube? A Japanese manufactured tube used in Luxman Amps back
in the day.

If no one has a spec sheet, I am looking for whatever information I can obtain. Absolute maximum plate voltage, maximum working voltage,
typical plate voltage used in the Luxman 3045 amp, Mu, Gm, Plate Curves etc?

Cheers

Pos
 
I was wondering if anyone has a data sheet for a 6240G vacuum tube? A Japanese manufactured tube used in Luxman Amps back
in the day.

If no one has a spec sheet, I am looking for whatever information I can obtain. Absolute maximum plate voltage, maximum working voltage,
typical plate voltage used in the Luxman 3045 amp, Mu, Gm, Plate Curves etc?

Cheers

Pos

I wonder if it is not a similar tube to the 12BH7, or maybe 6FQ7/6CG7 ?

T
 
I just did some searching around, and it looks like a 6CG7 is a suggested replacement.
Not sure of the 6240G pin-out (base=m9-03??) but a substitute looks do-able with some juggling:
  • If the gain is important and the the 6240G is handling input under 2VRMS, then I'd be tempted to try the 5670 at maybe Vak=200V, ia=7mA, Vgk=-4V
  • If the 6240G is handling big input signals >2VRMS, then the 6CG7 has lower gain but offers at least as much headroom at maybe Vak=200V, ia=9mA and Vgk=-6V

6240Gmu=35gm=3.5mSVak=200VVgk=-5Via=7mAheater=600mAbase=m9-03 (??)
6CG7mu=20gm=2.6mSVak=250VVgk=-8Via=9mAheater=600mAbase=9AJ
5670mu=35gm=5.5mSVak=150VVgk=-2Via=8mAheater=350mAbase=8CJ
 
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I know I'm late to this thread but there are a few options I've tried with my Luxkit A3600, which has the same original output (8045G) and driver/inverter (6240G) tubes. You can try either:
1. New reproduction 6240Gs here
2. NOS 6GU7s, which are a cheap, drop-in replacement (they are a 6.3V version of the 12BH7) - I bought quite a few and have found a well-matched pair which sound terrific
3. New (eg Electro Harmonix) or NOS 6CG7s or 6FQ7s, which are also drop-in replacements and, to all intents and purposes, equivalent.