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
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
Bottom of the last page. https://www.museum.uec.ac.jp/archive/tube/(010L) Rating of Japanese Receiving Tubes.pdf
Google is literally worthless anymore until you start wrapping quotes around terms.
Google is literally worthless anymore until you start wrapping quotes around terms.
I just did some searching around, and it looks like a 6CG7 is a suggested replacement.
In the searching around, I also found an Ebay seller asking a fairly hideous price for a used pair of 6240Gs, with no guarantee that they actually worked. This, folks, is why I design and build my own amps, with stuff that I know that I can get.
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
| 6240G | mu=35 | gm=3.5mS | Vak=200V | Vgk=-5V | ia=7mA | heater=600mA | base=m9-03 (??) |
| 6CG7 | mu=20 | gm=2.6mS | Vak=250V | Vgk=-8V | ia=9mA | heater=600mA | base=9AJ |
| 5670 | mu=35 | gm=5.5mS | Vak=150V | Vgk=-2V | ia=8mA | heater=350mA | base=8CJ |
Same pin-out as the 6CG7, so could try plug-n-play to see how it works
However, the electrical characteristics are more like a high rp version of the 5670 than a high mu version of the 6CG7 ....
However, the electrical characteristics are more like a high rp version of the 5670 than a high mu version of the 6CG7 ....
Thank you gentlemen for your time and efforts. Much appreciated.
I saw the ad for 2 tubes and the price. So much for NOS tubes these days.
Cheers and thanks again.
pos
I saw the ad for 2 tubes and the price. So much for NOS tubes these days.
Cheers and thanks again.
pos
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.
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.