I bought on ebay a while back some 6h2n russian tubes. They were said to be replacement 12ax7. I have not tested or touched these tubes for fear of wrecking my tester or equipment ( guitar pre amps) How can I tell what these tubes are and if they are just plug in replacements.

6H2pi, Russian near equivalent of the 12AX7 / ECC83. It has almost the same pin-out, but has 6.3 V heating on pins 4 and 5. Pin 9 is connected to a shield between both triodes.

The 6H2n has slightly higher gm then the 12AX7 / ECC83, giving it more power and authority than the 12AX7 / ECC83. Great tube for replacements.

But not direct replacement!

:I bought on ebay a while back some 6h2n russian tubes. They were said to be replacement 12ax7. I have not tested or touched these tubes for fear of wrecking my tester or equipment ( guitar pre amps) How can I tell what these tubes are and if they are just plug in replacements.
:

Hi Jon,
try the links below, I hope it's your tube...
Best regards,
Umberto

http://www.magictubes.ru/sprav/pdf/6n2p.pdf

http://oldradio.qrz.ru/tubes/russian/short/6n2p.shtml

Hi Jon,
If you are dealing with series filaments, the current consumption of 340 mA will be a problem. If it is used in a parallel filament circuit, you will need to manage the 6 volt spec on the filament.
As far as the tube tester, testing as a 12AX7 with the filament turned to 6 volts instead of 12 will be OK. If the tester tests the 12AX7 at 6 volts, you will need to get pin 9 isolated.

Best Regards,

Bill

All the Best,

Bill