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807 vs RK-39
8/12/2000 10:55:45 PMPascal Debien
I have a little 4 Watts single ended with 807 tube in output.
I found beautiful Raytheon RK-39 with white ceramic base.
One of my tube substitution handbook suggest RK-39 in place of 807.

Can i use RK-39 in my amp without risking any damage?
Sorry for my english
Thanks
Pascal Debien

8/12/2000 11:34:21 PMJohn McPherson
Hi,
The answer is a "qualified" yes.

The specifications for the two tubes are similar; heater characteristics are the same, the only signicant difference is that the 807 has a Maximum plate voltage rating of 750 volts, where the RK39 is rated only at 600 volts.

If your amps' B voltage is around 450-500 volts, there should be little problem.

The plate current rating is higher for the RK39 than it is for the 807, so you may want to calculate a fuse size to put into the output transformer circuit to protect the transformer from excessive current (normally not a real problem when tubes are as close as the 807 and RK39.)

Other minor differences between the two tubes are higher interelectrode capacitances for the RK39.

For all practical purposes, you will only be able to "hear" the differences between the two tubes performance.


: I have a little 4 Watts single ended with 807 tube in output.
: I found beautiful Raytheon RK-39 with white ceramic base.
: One of my tube substitution handbook suggest RK-39 in place of 807.

: Can i use RK-39 in my amp without risking any damage?
: Sorry for my english
: Thanks
: Pascal Debien



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