Need Opinions on New Build Voltage

[kd]

Just finished a ODS 101 non HRM and would like some opinions on the voltages I'm getting. The only change I made was at the dropping string. I put in a 4.7k resistor where the first 2.2K was supposed to go. I did it because the voltages were too high.

Plates: 443 volts biased at 39.8 ma.
Screens: 440 volts
V1a- 196.7 volts
V1b- 203.6 volts
V2a- 183.2 volts
V2b- 187 volts
V3a- 279.4 volts
V3b- 271.3 volts

Any opinions appreciated.

Thanks,
Ken

[ChrisM]

I'd get your V2 voltages about 20V higher. 20V - 30V.

From my research and experience
V1 likes from 190V - 200V
V2 likes 200V -210V

[Structo]

And apparently V3 the phase inverter likes to be closer to 300v so if you lower that first dropper it should raise them accordingly.

Do you have a 150K for the FET sim resistor?

[talbany]

Unusual for v2 to be that much lower than V1 especially if you have them separated with a 2.2k.. Have you tried several tubes in V2 as that one maybe pulling more current..

Tony

[kd]

Thanks for the input guys. I'll try a different tube at V2 before I mess with dropping string.

Ken

[mlp-mx6]

Double-check your V2 cathode resistors as well.

[kd]

One deviation from the ODS 101 schematic that I forgot about is that I'm using 120k and 110k plate resistors on the phase inverter.

Do you have a 150K for the FET sim resistor?

I'm using the 150K.

OK, I changed the tubes at V1 and V2 and that skewed the voltage. I went back to a 2.2K resistor between the screen cap and the PI cap so the voltage string is back to normal. Here is what I'm getting now.

V1a- 190.5 volts
V1b- 198 volts
V2a- 195.5 volts
V2b- 209 volts
V3a- 288 volts
V3b- 282 volts

Ken

[Structo]

Looks good to me.
Yes tubes can make all the difference sometimes.
I see as much as 10v difference between tubes.

[kd]

Looks good to me.
Yes tubes can make all the difference sometimes.
I see as much as 10v difference between tubes.

I wouldn't have thought that changing tubes would make that much difference, but seeing it first hand, I'm a believer.

Thanks for pegging it Tony.

Ken

[talbany]

Glad to help!!
Gotta watch it with NOS or pulls especially..

T