Good advices for a newbie (threading tools lathe)

[rendoman]

Hi! Thanks for advices!

Got no idea what the second filter at entry of first stage, the first high pass is good to avoid clip of audio in "low" freq, can the second be a Rf filter? I really don't know

I never study ef86 circuit, my audio circuit is a datasheet manual pcl82 amp, with pentode configuration at 272v anode, classic from Philips.
https://frank.pocnet.net/sheets/020/e/EF86.pdf
From this pdf of ef86 rg2 390k, something less Haumann, but pretty close, we can assume that the output voltage is 62v from this stage . I don't know why use a pentode as first stage and a triode of pcl82 as second before pentode modulator... I used triode + pentode for audio and then another pentode, this seems to me more logical, or maybe i'm wrong

I'm trying different flame coil, all with 1mm copper wire, different lenght and diameter, from 20 to 40, 10-40 turns. the only one that run is that on video (calculated as haumann, 8,9uH, if i remember correctly, hope i get in 3 weeks the Lcr meter i buyed from china). 30mm dia like haumann don't run, plus the 100uH on anode is completely unuseful. I used tons of uH more, with a hand made coil on toroid iron powder that help to keep the main coil "safe" . It seems strange, but with 2 coils, the first one near to anode becomes hot really fast.

I need at least 130v to ignite flame in second stage, g2 of pl509 (haumann circuit), that's the voltage applied to g2 of final tube.
you're right with tube quality, I tried change all 3 tubes with high quality new one, but nothing happens. I see another curious thing, I start only filament for 30 sec to warm up, then fire B+, it tooks 2 minutes for reaching the maximum current consumption. Tipical maximum flame with cold tweeter is 150ma, after 2 minutes current raise at 190ma and flame gains body. With this running config I got no problems, soft start, but no same weird things as with Others coils.

Music is not applied to plasma for now, because I want to take one problem at a time
Feedback is not so effective in my test, half or full, position in middle of tungsten - coil - up tip gives few results, even the 10nF , I changed with 6,8 3 and 1 nF but I didn't see something different.
Resistor G1 - loop changes polarisation of tube, this make differences.
g2 voltage in my setup is higher than Haumann, I can't fire till 130v, for sure it's a question of different tube, russian tube have poor datasheet , but i can maybe use data from LS50 german tube, the gu50 should be a copy of this

http://www.mif.pg.gda.pl/homepages/f...043/l/LS50.pdf

Next days I will make something for frame