Elrog 300B vs Takatsuki 300B tubes

Although it may not be analogous and although I am not sure that I understand the principles involved, I had a similar experience with my Ancient Audio 300b SET. It was built with a protective circuit that proved rather touchy. As I learned through trial and error (and with the help of the folks at Sophia Electric and AmtransJapan, the distributor of Takatsuki), individual pairs of 300b tubes were less likely to trip the circuit if they had a low measured plate current. There is a range of specs for all tubes that fall within the high and low acceptable limits. The manufacturers helped to cull out pairs that were the most compatible with my amplifier.

This evening, from about 7:00 PM on my voltage has been fairly steady at 122.3.

The highest reading I observed all day was 123.3.

07-07-15: Tmmvinyl
Am I correct that I should not be using my Takatsuki tubes in the Frankensteins given my high voltage readings?

I haven't been able to find a datasheet or detailed specs on the Takatsuki tube. Can anyone provide a link to that information?

Best regards,
-- Al

A point to keep in mind regarding the AC voltage measurements some of you have been making: Although a digital multimeter may provide 4 digits or more of resolution (i.e., to tenths of a volt when reading voltages in the vicinity of 120), its readings are by no means necessarily accurate to anything remotely close to tenths of a volt.

For example, the B&K 2703C, which lists for $46 and is produced by a very reputable company, provides 0.1 volt resolution on the scale which would be used to measure AC power, but its specified accuracy on that scale translates to +/- 2.9 volts when measuring 120VAC!

Which reminds me, I've got to order myself a good Fluke DMM. My old Triplett analog multimeter just won't cut it when it comes to accuracy :-)

Best regards,
-- Al

Al,
Thank you for your continued contribution to this thread. I do not have a Data Sheet for the Takatsuki 300B tube, but I can share the test results for one of my matched pairs if that would be helpful.

For example, the plate volts Ep vdc test result was 300 for each tube; DC plate current lp mAdc was 73 and 73.1 for each tube; AC plate current lp mAac was 6 for each tube, Bias volts G1 vdc was 60 for each tube; Grid #1 leakage uA was 0.29 and 0.27 for each tube; Tube gain Mu was 3.6 for each tube; Plate resistance RP ohms was 0.6K for each tube. Do these numbers help? Is there another number I should look for?

Thanks again.