I live in Brazil and didn't find the LM334. I have found the LM234.
Via datasheet they are the same family, only changing the temperature range.
But I'm having problems. These components seem very fragile.
The LM234 or LM 334 are my great problem. Suddenly it stops working, the voltage on pin 1 and 6 (of ECC82) goes to 80V and the voltage in pin 9 goes to 1V.
I bought 10 from China via ALI EXPRESS.
https://pdf1.alldatasheet.com/datasheet-pdf/view/22753/STMICROELECTRONICS/LM334.html
https://www.ti.com/lit/ds/symlink/lm334.pdf?ts=1674803089952&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FLM334
Is it possible to replace the LM334 (in the outside of the tubes) using a traditional method, using a resistor and capacitor?
Another problem I got. The range of the bias is too short. I've getting 240mA with the minimum bias -39V
Talking with Roy, he help me and I change the 27k resistor for 15k, so I can get -28V
My tubes are Russian Tung-Sol, EL34B.
Best Wishes
FAB