Will this circuit work for the screens on the ART-13?

[KR4WI]

Hello: I am trying to get an ART 13 on the air, I found a circuit on www for it but I don't have the junk box that he had. So I was wondering if this circuit would work?It is for the screen supply. It needs 400 volts.

Another question, does anyone know of a free program that I could download and use to create circuits?  Thanks for any help. or thoughts. Matthew KR4WI

[WU2D]

Hi Matt,

Congratulations on bringing an ART-13 back to the bands!

It looks like you have everything you need looking at your schematic. The 1N4007's should handle the job with only a couple of resistors feeding the bridge. You can series up 8 diodes using the cap and resistor across each diode to increase the PIV, making a larger bridge. Using just 4 diodes in the bridge should work though.

The medium voltage screen (and oscillator) supply for the ART-13 is the most critical supply of the three which are required to run the radio. It must be well regulated and clean. I have collected power supply schematics and have come up with a few that allow you to use odd ball transformers at various voltages and still come up with 400 VDC. The best transformer is a big old TV job or a surplus military transformer which is capable of 300 mA to a half an Amp..or half of that for the CT transformers.

I actually run close to 450 VDC. The caps can be in series together to form higher voltage as you show. The caps that you have should work fine with 100K resistors across them. Two should do the trick. You do not need 4 in series for this voltage.

I use the E circuit with a heavy bleeder and lots of capacitance with a big TV transformer. It is well regulated under load. 

Good Luck - and don't get zapped!

WU2D Mike

[KF9CM]

I'm glad to see more Hams bringing The ART-13 back to life. On my site I have several mods for the ART-13 and regulating the screens is one. Please feel free to download anything you want. click here:
www.kf9cm.com

TNX
Gary KF9CM

[KR4WI]

Thank You : Mike and Gary, This is what I needed. I have the 28 volt supply finished and have seen the tubes light up and the knobs turning with the autotune, I am working on the 400 volt now, and then I will start on the 1250 volt supply, Mike, would you have some schematics on the HV supply like you posted above? I would also like to see them if you do. Thank You Gentlemen. Matthew KR4WI

[WU2D]

Matt,

I dug up my power supply schematic that I drew in 1992 - geez that is a long time ago. A couple of things that you notice on this: I was really lazy on the HV. I simply used C - thats right no filter choke, no Pi network. This has to result in some hum , but I have not heard any negative comments. I suggest that you put in a choke!

The second interesting thing is the time delay circuit. Really complex eh? It is a lifesaver on the tubes allowing the fils to light up a solid minute before the MV or HV are even allowed to come on.

One thing is not shown. I eventually added a variac to the HV rack with meters so I could monitor Voltage and Current and I always start with 0 volts on the HV and bring it up only as high as I need. For instance for AM, I run 1500 VDC. For low power CW, I run 1000 VDC. For High power CW I run 2000 VDC.

When you turn the PS on, only the 28V lamp comes on and you hear the fan come on. After a minute, you hear a click and the MV lamp comes on. Then I turn the variac up to the HV I want to run.   

This conservative approach has paid off since the ART13 is still happy and I have not lost any tubes or the autotune. In fact I still am running the original military 811's and never got around to trying the 811A's that I bought.

Mike WU2D

[KR4WI]

Mike: Thanks, Its good to keep stuff. I dont know why my wife thinks othewise, HE HE It looks like and sounds like this is the one for me also, I will try building it and see how mine turns out. I still have original 811s in mine also, I hope to get it working I need a medium power tx, and the art-13 seems to suit the call for that. Hope to talk to you on the air soon with it. Matthew KR4WI