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April 04, 2020, 08:46:06 AM

Author Topic: Heater voltage  (Read 1860 times)

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Offline Laudanum

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Heater voltage
« on: May 28, 2012, 07:27:43 AM »
I swapped tubes from some NOS Russian 6H23n-EB's to Amperex 6DJ8's and need to adjust the heater voltage accordingly (thanks again for the reminder Joshua).  My Seduction is on a conditioner with voltage regulation (not super tightly regulated)  that kicks in around 113V and brings voltage up to 120 - 122V.  I just checked with line voltage at 113V and had right at 5.23 volts on the 6DJ8 heaters.  At 122 volts line voltage, heater voltage was right at 5.72 volts.   So, Im probably going to have to split the difference here.  Should I shoot for a minimum of 5.7 volts on the heaters at what should be the minimum 113 volts ine V (before AVR kicks in)?  Or should I shoot for a maximum of 6.3 volts at 122 volts line voltage (I dont think I've ever seen the AVR kick it up beyond 122 V). ?     

Just in case I wont be able to stay within the 5.7 - 6.3V range perfectly,  what Im asking is ... would it be better to fall a little below 5.7 volts minimum (say 5.6 volts)  on the heaters if it meant keeping the maximum below 6.3 volts?   Or better to exceed 6.3 volts by a small amount in order to keep the minimum at 5.7 volts or above?   
Desmond G.

Online Paul Birkeland

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Re: Heater voltage
« Reply #1 on: May 28, 2012, 09:45:05 AM »
How long does it take for the voltage regulator to kick in?

If it's a matter of seconds, then shoot for 6.0V at your regulated output voltage.

If not, how long does it take to settle?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Grainger49

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Re: Heater voltage
« Reply #2 on: May 28, 2012, 10:04:00 AM »
PJ posted on this recently but I can't remember the thread.  Try searching for Paul Joppa and heater voltage.

Offline Laudanum

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Re: Heater voltage
« Reply #3 on: May 28, 2012, 10:55:21 AM »
I think the Voltage reg. kicks in as soon as line voltage drops to 112 volts.    Regulated voltage is 120 volts +/- 5% I think but ive never seen it go beyond 122 and it holds 120 pretty well unless voltage really drops out a bit below 110 volts.  I believe that it kicks back off at 117 volts.    

Anyway, I just tried a .75 ohm and .6 ohm.  Line voltage was up at 118 volts (voltage reg. off)  and heater voltage was 5.98 volts.  That was with the .6 ohm resistor so I think it's probably a good choice.  
Paul J. suggests .68 ohms at 115 volts and .91 ohms at 120 volts as starting values with 6DJ8.   .6 seems close enough at 118 volts.  I think heater voltage should stay within 5.7 - 6.3 volts with line voltages from 113 to 122 Volts.  With the .75 I think it may drop a little below 5.7 if line voltage dips to 114 or 113 volts  but either would probably work and I dont have anything in the middle.  
I think it'd probably be splitting hairs anyway.  I probably am already   :D
Desmond G.