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Floating cathode and heaters power supply
Floating cathode and heaters power supply
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Old 24th November 2020, 03:26 PM   #1
Bigwolf is offline Bigwolf
diyAudio Member
Join Date: Jan 2020
Default Floating cathode and heaters power supply

I read what "each tube have floating cathodes should use independent heater".
I do not understand why. For example, I use 3 tubes outside of audio path signal, one have 250V cathode potential (EZ80 rectifier), other cathodes connected to GND (EM800 indicator and TG1 thyratrone).
Each tube maximum cathode to filament voltage:
EZ80 500V
TG1 0 to -50V
EM800 +/- 100V

So, in that case I can connect all 3 filaments to one supply.
Is it correct, or should I connect middle of winding to ground, because EZ80 may give some positive voltage on heater(?), but it is not possible for thyratrone.
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Old 24th November 2020, 06:59 PM   #2
duncan2 is offline duncan2  United Kingdom
diyAudio Member
Join Date: Mar 2013
Location: Scotland.
Not ideal if you want reliability in your power supply and amplifier as its down to the heater/cathode insulation of the EZ80 but its done , not something I would do regardless of other opinions considerable stress on the heater-cathode insulation at 300 volts .

For radio builders/repairers like myself earlier tubes for rectifier heaters had separate winding's .

How much do you trust a Chinese EZ80 ?

When you have a valve (tube ) tester like I have of an AVO VCM MK4 you come across low insulation again and again .
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