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Old 5th September 2013, 10:23 PM   #21
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Do you have a mac? I know I have ran PSUD on my macbook.
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Old 5th September 2013, 11:20 PM   #22
multi is offline multi  Australia
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I made several Transformer testers. just two big 3000ohm 200 watt pots and a 10 ohm resistor to check current draw.
I can test: choke input, bridge rectifier, center tap transformers and voltage Doublers. Can test at any current draw. very good if you need to drop voltage just put small caps before the choke input and increase cap size to get higher voltages.
Much more accurate than doing simulations. I have a lot of ex military power transformers to test.
Phil

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Old 6th September 2013, 12:03 AM   #23
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I cut one top plate today for testing. This will make no sense to some, but it is actually easier for me to build on an amp chassis than make breadboard apparatus, etc.

It was just too hot today to paint the plate. Yes, it gets too hot to paint metal here in Dallas.
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Old 6th September 2013, 02:04 AM   #24
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I had occasion to upload the attached "hen scratch" graphic over on AA. It seems that it is useful here too. Measures have to be taken when choke I/P filters are combined with SS diodes, to avoid destruction by inductive kick back spikes.

A high current supply is needed for a PP 6550 stereoblock. A pair of sockets are needed for 2X 5R4s, which will turn on almost as quickly as "sand" does. Since 2 sockets are a given, consider using a pair of damper diodes, which start slowly, for B+ rectification. The 6CJ3 is a "monster" and a pair will comfortably supply 600 mA. of B+. The Tube Store has 6CJ3s and the Novar sockets they mount in at reasonable cost.

The SAFE way to employ damper diodes is to tie each cathode to an end of the heater and energize the heaters with a dedicated filament trafo that has a superior HIPOT rating. Triad's VPL12-4000 fills the requirement and is favorably priced. When I checked Mouser a few hours ago, they had 2X VPL12-4000s in stock.
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Old 6th September 2013, 03:21 AM   #25
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Hi Eli,

So, you are saying to use two 6CJ3s to form a full wave? Novar sockets are no big deal. I have a quad pulled from an old Fisher amplifier. Probably a NOS quad of sockets also. The main issue is where to put that Triad.

The 6CJ3 is OK to use with a 1200VCT power transformer?

Use the triad to power the filaments on the 6CJ3s and the power transformer filament winding for the power and driver valves?

Blair

Last edited by deicide67; 6th September 2013 at 03:37 AM.
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Old 6th September 2013, 04:07 AM   #26
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Quote:
The 6CJ3 is OK to use with a 1200VCT power transformer?
A 1200 VCT rectifier winding needs diodes whose PIV is not less than 1698 V. You always leave yourself some breathing room. So, call 2 KV. whats needed. The PIV rating of the 6CJ3 is a whopping 5.5 KV., design maximum. "It's a piece of cake."

Take a look at GE's 6CJ3 data sheet. Notice the remarks about a diffusion bonded cathode, which is highly resistant to stripping. There is every reason to believe that 6CJ3s will have lengthy service lives.

Quote:
Use the triad to power the filaments on the 6CJ3s and the power transformer filament winding for the power and driver valves?
Correct! If the power trafo has a 5 VAC winding, voltage multiply it to get the bias (C-) rail.
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Old 6th September 2013, 04:11 AM   #27
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I'm only mentioning because your questions make it seem like this is your first choke input supply and it's kind of a doozy of a first and it looks like you'll be trying it out in the case.

I'm sure you know but the supply rises to 1kV + if unloaded (I don't know the arc length of 1kV). If you have your heart set on it then I wish you the very very best with it.

Like theGimp says definitely model it. You can put in the range of loads the supply will see too and see the performance with various chokes as well as SS vs tube rectification. And nothing goes boom. Of course nothing beats trying it out to see what happens for accuracy.
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Old 6th September 2013, 04:11 AM   #28
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Awesome! I will actually have an extra 6.3V and 5V winding in the end because one 6.3V winding is about 8A in my power transformer.

What is the C- rail? The negative bias supply?
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Old 6th September 2013, 04:18 AM   #29
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Quote:
Originally Posted by homeskillet View Post
I'm only mentioning because your questions make it seem like this is your first choke input supply and it's kind of a doozy of a first and it looks like you'll be trying it out in the case.

I'm sure you know but the supply rises to 1kV + if unloaded (I don't know the arc length of 1kV). If you have your heart set on it then I wish you the very very best with it.

Like theGimp says definitely model it. You can put in the range of loads the supply will see too and see the performance with various chokes as well as SS vs tube rectification. And nothing goes boom. Of course nothing beats trying it out to see what happens for accuracy.

Yes and no. I've built dozens of amps and "tuned" B+ with C1 in front of the L1. Nothing this high voltage though. Mostly in the 350-500V range.

It has always been iron that was negligible also. I'm building these for me, so it's a bit more important

Kind of a no compromise type thing. Lots of $$ bolted to the plate, so I want to ask the right questions.
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Old 6th September 2013, 04:41 AM   #30
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I can certainly see the investment. I don't mean to be a drag on your project. Having a choke input filter doesn't add to the no compromise part necessarily. But if you're all good to go with the rating on your transformer and your bleeders are secure and well over rated. It looks like you're going to get excellent advice. Then all I can say check everything over and over and be careful. Sorry, I can't help myself.
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