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Old 6th February 2013, 04:14 PM   #2461
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I will use filament bias so not necessary as I supposed right?
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Old 6th February 2013, 05:14 PM   #2462
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I use a small grid stopper, 390R. It may not be necessary - I haven't looked into this. You absolutely have to have a grid leak or the tube will oscillate. I have a 100K pot on the input so that acts as grid leak.

You can use up to 60uF cap with the AZ1. Normally a small cap is good so you have choke input or "virtual" choke input. If you do this you have to make sure the choke is in regulation - may need to be followed by a resistor to earth probably somewhere round 10K and needs to have sufficient wattage.

But since this is followed by chokes, caps and a shunt reg (or DN2540 + glow tube), it may not be too audible. If you need to keep the HT high enough then sure, you can use a bigger first cap. If you have plenty of voltage you might go for a "purist" approach and use choke input or a cap up to 1uf or so. Plenty of choices, and they all work.
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Old 6th February 2013, 05:17 PM   #2463
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Thanks Andy, the problem is that I have a tx of 125VAC 100W.

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Felipe
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Old 6th February 2013, 05:18 PM   #2464
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I don't know if go for voltage doubler or use the 2nd tx 125vac 100W?
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Old 6th February 2013, 05:41 PM   #2465
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Are you saying you have two transformers both 125vAC? You could put the secondaries in series to get 250v. You would need to get the phase right - if you have 2 identical transformers the end of the first winding should go to the start of the second winding.

Last edited by andyjevans; 6th February 2013 at 05:43 PM.
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Old 6th February 2013, 05:43 PM   #2466
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Yes. I know wich one is the phase so I can connect in series to get 250VAC.

Last edited by merlin el mago; 6th February 2013 at 05:47 PM.
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Old 6th February 2013, 06:03 PM   #2467
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My PSU target for B+ is 170VDC 30mA for Salas SSHV2, what about attached PSU?
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File Type: png 2 x 125VAC #26.png (158.3 KB, 233 views)
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Old 6th February 2013, 06:07 PM   #2468
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Quote:
Originally Posted by andyjevans View Post
I use a small grid stopper, 390R. It may not be necessary - I haven't looked into this. You absolutely have to have a grid leak or the tube will oscillate. I have a 100K pot on the input so that acts as grid leak.

You can use up to 60uF cap with the AZ1. Normally a small cap is good so you have choke input or "virtual" choke input. If you do this you have to make sure the choke is in regulation - may need to be followed by a resistor to earth probably somewhere round 10K and needs to have sufficient wattage.

But since this is followed by chokes, caps and a shunt reg (or DN2540 + glow tube), it may not be too audible. If you need to keep the HT high enough then sure, you can use a bigger first cap. If you have plenty of voltage you might go for a "purist" approach and use choke input or a cap up to 1uf or so. Plenty of choices, and they all work.
Andy if I not use pot wich value for grid leak resistor 100K?
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Old 6th February 2013, 06:19 PM   #2469
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I'd say more like this, with 250v secondary. I use all polypropylene caps - motor runs. The 10K resistor after the first choke is probably overkill - it depends on what the circuit draws in terms of current. I don't know what the shunt reg draws. You could leave out the 1uF input cap or use somewhere between 0.1 and 1uF. I like to put a small cap in there. Choke input with 250v secondary should end up giving you just over 200v with all the chokes, caps, resistors etc, before the shunt reg. That would be fine for a DN2540 plus 150v glow tube. Don't know about a Salas reg - never used one. If the voltage ends up being low (the resistor after the choke will lower the voltage depending what size it is) you can increase the size of the first cap. You need to read about how to keep chokes in regulation and look at the formula for choke input. For cap input above about 4uF it probably doesn't matter. I'm being a bit vague about this because I have a Mac and can't run the PSU calculator.
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Last edited by andyjevans; 6th February 2013 at 06:28 PM.
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Old 6th February 2013, 06:38 PM   #2470
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The SSHV2 reg draws itself 20mA, psud2 can't simulate the 10K 14W but can simulate a constant current: do you know the mA to calculate with psud2?
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