If all will be correct its going to ask around 2.7-2.9R. Rset way different than 2.8R center value is wrong.
Better, shorter wiring, and power resistors. 5.6R//5.6R 2W each if you got, also sufficient. The closer the Rset to the Adj & Vout LM317 legs the better.
I guess not because the filaments when reach the voltage lights, but tomorrow I will use a dummy load resistor 14R 10W to be sure.
I bought the tubes brand new Tungsol reissue.
I bought the tubes brand new Tungsol reissue.
Using dummy load 14R only reach 3.1V so only 221mA and of course still oscillates with alligator clips.
About tight wiring and parts proximity issues were your troubles as it looks. You need set little more current to go about 6.1V? Both tubes achieve about the same Vh?
Keep in mind the particular 317 Vref value you now measure so to calculate what Rset more predictably. Still at 1.2416V?
True but you have accurate top of the line Brymen meter you can REL its test leads to zero first and then see.
2.7R 5W single should bring the particular filament nearer to 6V. Spec +/-10% on 6.3V nominal gives 5.7V-6.9V acceptable range. It is even better to stay +/- 5% if you can 6V to 6.6V.
Not, VRef 7.62 tester probe + to output & tester probe - to GND. 6.317V at filaments, Rset resistor 2R74.