Heater max voltage

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tomtweed
Junior tube assistant
Posts: 13
(2/21/04 3:36 pm)
 Heater max voltage
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 Hi all...
What would be considered max heater voltage for 6.3 and 5volt supply? I have a few old (115v) primary transformers I would like to use. My line voltage is around 122-124v most of the time. This gave me apx. 5.7-5.8, and 6.9-7.0. I know vintage amps seem to run fine, and I don't want to run through a variac or light bulbs. Most tubes 5y3gt(nos)6v6,12a* types.

Thanx tons for your help
TT
 
Tiny Daddy
I will work on all amps
Posts: 510
(2/21/04 8:36 pm)
 Re: Heater max voltage
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 "5.7-5.8, and 6.9-7.0" seems highgher than I would expect even with the higher line voltage. Are you measuring the voltages with no tubes connected? Voltages will drop with tubes installed.
 
tomtweed
Junior tube assistant
Posts: 14
(2/22/04 10:44 am)
 Re: Heater max voltage
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 Yes...no tubes installed. This is right out of the transformer on the bench, not in any circuit at all.

TT
 
Andy Poupart
Senior tube assistant
Posts: 121
(2/22/04 9:00 pm)
 Re: Heater max voltage
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 Personally, even with tubes installed I think the voiltages you'll get will be too high. It's the same problem as with Hammond PTs, with their 115V primaries.

Why not use a little 5V filament transformer and drop your line voltage 5V to 117-119V. I've done that with a HiFi amp I built using Hammond iron. I used RG Keen's Vintage Voltage circuit, available here:

RG Keen's Vintage AC article
 
tomtweed
Junior tube assistant
Posts: 15
(2/23/04 12:20 pm)
 Re: Heater max voltage
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 Thanx Andy...
This is a great idea, and good info. I think I can do this circuit o.k. Another great item for a "bag of tricks".

Thanx again
TT
 
 
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