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Re: 5AR4 Issues

First, consider running your power supply design thru Duncan Amps' simulator (www.duncanamps.com). It will quickly tell you if you are outside of a 5AR4's parameters and is a fantastic program (free too!).

I've heard better reports about the Sovtek 5AR4's and most recent Chinese production. I have had repeated problems with chinese 5AR4's, and have given up on them. By the time you play with 3 or 4 to get one good one you might as well just buy a used British (or Japanese) GZ34 and be done with it.

It's too late with this project as you've already made up your chassis, but consider damper diodes in a future project. They are inexpensive and rugged.

5U4's are a fine rectifier, and you can get slow turn on several ways. One nice trick is that if you have a separate transformer for the B+ use a inrush current limiter. Mouser carries a good selection and you can play with the value to get a nice slow rise in B+.

I've also used a small timer circuit that keeps a moderate resistor in the power supply circuit during turn-on, then shorts it out in 15 seconds. See http://www.kitsrus.com/kits.html#k152 (photo above)as one example of a suitable circuit.






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  • Re: 5AR4 Issues - Gary Kaufman 08/9/0209:45:25 08/9/02 (0)


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