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Old 11th March 2010, 12:26 AM   #121
nhuwar is offline nhuwar  United States
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Location: Cypress Texas
You know you can use the chokes on the grounded side of the b+ supply.

Make your voltage requirement a lot easier to meet.

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Old 11th March 2010, 04:14 AM   #122
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I'll be using Lundahl 1638 chokes. Consulting with Kevin (US Lundal distributor), I should be ok with the voltages and the currents they'll be used with. No value will be exceeded.



Originally Posted by ron parola View Post
Jeffery, Whose chokes are you using for the HV power supply. So far I've found nothing commercially available at these voltages. I'm hoping NOT to have to special order any. Thanks Ron p
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Old 11th March 2010, 04:55 PM   #123
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Thanks! Ronp
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Old 18th March 2010, 05:21 PM   #124
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Methinks it's just about there. Added a delay and slow start circuit to the megabeast. Turn on sequence for upper supply:
1. turn on main power switch... Amperite 75 second delay to primary while 866a MV rectifier filaments heat.
2. Amperite trigers and secondary 6.3v sets the 25 second solid state 555 based timer (Sophia Electric). **In case of a power blip, the Solid State device will reset and give some time for the heaters to warm, as the Amperite will probably be too hot to give the 75 second delay**.
3. Sophia trigers and separate 6.3vct tranny heats the 6CG3 damper diode.
4. damper diode slowly heats then ground circuit in upper supply is made and full B+ is availible.

Note 1 .... The center tap of the damper diode filament transformer is biased to the cathode as to keep their potential at the same level. The Damper diode has a max rating of 900volts Cathode to heater w.r.t heater being negative (relative to cathode).

Note 2 ...I liberally use CL80's for turn on current surge for the big tranny as it's a toroid and to add just a bit of ramp up time. Redundant, maybe, but cheap and they only cost a couple of volts, not to much to worry about. The Damper Diode also costs about 20 volts or so.
The lower supply uses a 5852 Bendix, a Aerospace version of a 6X5GT. It has a 45 second heat up time, so it can be used as-is for the 20B.

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Last edited by Jeffrey Davison; 18th March 2010 at 05:27 PM.
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Old 28th October 2010, 05:37 PM   #125
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Construction pics ???
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Old 1st November 2010, 08:52 PM   #126
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Hello. I am also curious to hear how this amp turned out. The switches were thrown, the anticipation was building, and....
Thanks for sharing. This has been a fun thread to follow.
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