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 Post subject: initial voltage check
PostPosted: Tue Apr 09, 2019 10:31 pm 
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I got pilot light, heaters to all sockets, and mains wired up. Ran the HV secondaries to a terminal strip for quick testing.
Wall voltage is 121VAC, heaters 6.7VAC, and high voltage is 711 VAC.
According to build manual I should be running "10-20% higher" than the PT schematic for HV, which from what I can tell says 690. Am I correct in thinking I should be seeing at least 760VAC? Want to confirm before going too much further.


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PostPosted: Thu Apr 11, 2019 7:51 am 
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Yes, should be higher but it. depends on your mains voltage. 120V mains is the reference.

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PostPosted: Thu Apr 11, 2019 9:13 am 
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Mains is 121. I'll try a different meter and check the HV again. Maybe I am reaching the upper limits of my VM. I'm pretty confident this may be the issue. Also, I didn't read each side to ground; that will cut the voltage reading in half which should definitely fall within range of the VM, so maybe if I do that I will get ~380-400VAC on each side.

With as bare-bones wiring as I have now, there really aren't any other variables with the amp build that could cause a low reading, other than the PT itself.

I doubt its the PT...likely a VM issue.


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PostPosted: Thu Apr 11, 2019 3:56 pm 
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I checked each side of the HV secondary to ground and get 355VAC on one meter and 353VAC on another. these are well within max limits of the meters.

would hate to proceed with the build only to find out that my voltages are too low (HV ~710VAC vs the expected 750+) and then need to change out a lot of resistors along the power rail just to get plate voltages in the expected range.
any ideas? what's the best course of action at this point? proceed with setting up the diodes and see what I get after rectification?


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PostPosted: Thu Apr 11, 2019 5:59 pm 
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more info:
no filter caps, no OT in circuit
black/red + white/red wired to power switch.
solid black and solid white connected to mains (neutral)
line from mains connected to fuse. fuse to power switch.

heaters/LED to heater supply (all good there; 6.7VAC)

HV secondaries temporarily wired to terminal strip. 710VAC

Mains voltage 119.8-120.5


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PostPosted: Sun Apr 14, 2019 8:02 am 
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Suggest you continue the build . The final B+ will be determined by tube HV load and bias .

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PostPosted: Sun Apr 14, 2019 10:37 am 
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:thumbsup:


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