6240G Data Sheet?

[Joe Dawson]

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?

Keep on Truckin

joe

 

[TriodeLuvr]

Don't know the plate resistance.

 

[gadget73]

Is this the twin triode that gets subbed with a 6cg7?

 

[Blue Shadow]

Is this the twin triode that gets subbed with a 6cg7?

Driver tube in the 3045s

 

[Blue Shadow]

Just one of the many chunks of internet info I have collected over the years for the MB3045 amps I have. Applicable to other amps using the 6240G I expect. Posting so folks can comment. This is from the Luxman . io group discussions.

Luxman 6240G vs. 6CG7

I just came upon three NOS 6240G tubes. Better still these were the last stock from the service dept of the local importer so I believe they are the most recent production stock made too.

So I thought I better test them and post the results for posterity while they are still new!

The 6CG7 is usually nominated as the best substitute and has worked for me in several amps but recently I had a pair of MB3045s that became somewhat unstable with 6CG7s in.

I compared the 6240Gs with some NOS USA made GE 6CG7s.

Here are the results:

With 250V B+ and Vg of -8V the GE tubes gave Ip = 5.5-6.0 mA and Gm of 3.0

For the same Ip the 6240G required just -5.0V Vg and tested this way gave Gm = 3.6

So the Gm isn't a problem. But I tested a 6CG7 with the lower -5.0V Vg and it passed 13mA...more than twice that of a 6240G for the same setup.


So it seems the way to sub a 6CG7 for a 6240G is to change the cathode bias resistor to give a proportionately higher Vg.

John Corneille
Melbourne Australia

6cg7 NOS GE 250V -8V = 5.6/6mA and Gm=3.0/3.0
(but gives 13mA at -5V)

6240G NOS 250V -5.0V = 5.5/6mA and Gm = 3.6/3.6

 

[Joe Dawson]

Thanks for the info Gents. Much appreciated.

Rp will vary with conditions so no sweat.

Thanks again guys.

Keep on truckin

joe