elevated filament voltages

[rayma]

rayma; see post 12 for the link to the schematic, then go to post 7.

ruffrecords; Just looked up ECL86/6gw8 spec sheet. Both Vhk for both section should be a max of 100v. Looks like to hit the best spot as rayma indicated would be right around 115v for the dc elevation with only one source. It would be easy to add a new source for V1. What would be the result? Does this affect the operation/sound of the tube? Haven't lost a tube in these positions.

Don't know why they used such a high voltage, exceeding the 100V rating.
I would use +115V but the manufacturer thought differently.

 

[ruffrecords]

Ok, if there is only one filament winding, you have to elevate it to about +115 VDC to meet the requirements for all the tubes.
Preferably, there would be a separate winding for the tubes with high cathode voltages.

Except on the schematic there are two of them. One referenced to 0V and one elevated.

Cheers

Ian

 

[rayma]

Except on the schematic there are two of them. One referenced to 0V and one elevated.

The 6GW8 has both high and low cathode voltages in one envelope.

 

[ruffrecords]

The 6GW8 has both high and low cathode voltages in one envelope.

Which is unfortunate because the because the datasheet says Vhk is 100V. I cannot see a heater elevation voltage that meets this spec and allows one cathode to sit at 225V and the other near 0V.

Cheers

Ian