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December 06, 2022, 10:39:45 AM

Author Topic: 2A3 filament voltage...  (Read 879 times)

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Offline Paul Birkeland

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Re: 2A3 filament voltage...
« Reply #15 on: January 27, 2022, 02:46:57 PM »
I would just parallel a 0.47 ohm 2-3W resistor with what you have now.  That would nudge the voltage up a little more.  Non-inductive resistors are slightly worse in this position than inductive wirewounds btw.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Ivan303

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Re: 2A3 filament voltage...
« Reply #16 on: January 27, 2022, 03:18:45 PM »
I would just parallel a 0.47 ohm 2-3W resistor with what you have now.  That would nudge the voltage up a little more.  Non-inductive resistors are slightly worse in this position than inductive wirewounds btw.

Any hints on the brand you guys are currently using?  Mills being non-inductive ww as I recall?

Offline Paul Birkeland

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Re: 2A3 filament voltage...
« Reply #17 on: January 27, 2022, 03:49:34 PM »
The manual was shot with Vishay LVR03, though we may be shipping the kits with something else since those seem to be hard to find now.  Can you post a photo of what you have? (I'm not in the office super frequently anymore)
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Ivan303

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Re: 2A3 filament voltage...
« Reply #18 on: January 28, 2022, 05:33:00 AM »
The manual was shot with Vishay LVR03, though we may be shipping the kits with something else since those seem to be hard to find now.  Can you post a photo of what you have? (I'm not in the office super frequently anymore)

Seems I have a 1V difference this morning in AC line voltage between the work bench (121.4AC) in the garage and the 'casita' a mere 10 feet away (120.6AC) where the system resides, which could explain some of my confusion about our home's line voltage as well as the filament voltage as I made measurements of both in two different places.

In the future I will take measurements in-system along with line voltage measurements taken at the same location.  Also will only take measurements of the filament voltage when the system is warmed up for a few hours, as Paul suggested.  System us usually on from about mid to late morning and is turned of late evening. 

It's sounding good enough these days that it gets a workout.  While part of the house, the 'casita' is an attached 400 sq. ft. room/space added after the house was built (with an additional AC switch box) and as it is attache to the garage one can 'crank it up' and bother no one in the rest of the house. 

Attached is a pic of the 0R10 resistor.



Offline Paul Birkeland

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Re: 2A3 filament voltage...
« Reply #19 on: January 28, 2022, 05:48:51 AM »
That's a Vishay LVR03.  Those are more or less NLA, but you could use a Vishay AC series in parallel with it:

https://www.mouser.com/ProductDetail/Vishay-Draloric/AC03000004707JAC00?qs=sGAEpiMZZMtlubZbdhIBIBpEgVvVFfjkwWNI4DU7AcM%3D
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Ivan303

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Re: 2A3 filament voltage...
« Reply #20 on: January 28, 2022, 06:21:10 AM »
That's a Vishay LVR03.  Those are more or less NLA, but you could use a Vishay AC series in parallel with it:

https://www.mouser.com/ProductDetail/Vishay-Draloric/AC03000004707JAC00?qs=sGAEpiMZZMtlubZbdhIBIBpEgVvVFfjkwWNI4DU7AcM%3D

Thanks and done.


Offline Paul Birkeland

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Re: 2A3 filament voltage...
« Reply #21 on: January 28, 2022, 06:41:48 AM »
A higher voltage rated capacitor on the socket from the same series will also usually trim the voltage up slightly.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Ivan303

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Re: 2A3 filament voltage...
« Reply #22 on: January 28, 2022, 07:00:58 AM »
A higher voltage rated capacitor on the socket from the same series will also usually trim the voltage up slightly.
 
Oh NO!  Please don't start me Cap Rolling again!!!    OK, it's a reasonably priced electrolytic so...

Last pair of caps I rolled into these amps cost me $100!  But worth it.  Generally, I don't expect much difference with coupling cap changes, be they film cap to film cap, but those green Solen Teflon caps are magic.  Smooths out the top end while still providing plenty of detail.  For the most part I find with 'smooth' and 'detail' you can only have one or the other while the Teflon seems to allow one to have both.




Offline Ivan303

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Re: 2A3 filament voltage...
« Reply #23 on: February 02, 2022, 12:01:54 PM »
Line voltage seems to be between a low of 119.4VAC to 123.5VAC over the last days (most of this during the day time but more measurements will be done for sure.

With a .56 Ohm 3W  ww resistor added in parallel with the existing 0R10 3W ww AND an additional Nichicon 10,000 ufd 12V electrolytic in parallel with the existing Cap, I get a heater/filament voltage of 2.521VDC when the line voltage is 121.5VAC.  We'll see what the filament voltage drops to if and when the line voltage drops to 119.5VAC or 120VAC later tonight.

Line voltage is about 121VAC +/- 2% and that puts us pretty much 2.5VDC +/- 2% so we are fine!
« Last Edit: February 03, 2022, 11:46:11 AM by Ivan303 »