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Letters to the Editor

How About a Switching Tetrode Power Supply?

0 In reference to Ian White, G3SEK's excellent article on powering tetrodes:1 Has anyone considered using a modern switching supply for the plate supply?

A switcher would:

1. Save a lot of weight.

2. Permit power-factor correction, getting more power out of a given primary circuit.

3. Give a well-regulated supply with current limiting.

4. Use 1000 times smaller filter capacitors, for 1000 times lower-energy pulse in a flashover.

5. Permit very quick shutdown in the event of a flashover, by shutting down the primary-side converter.

The problems I see are:

1. Obtaining high-voltage, fast-recovery rectifiers.

2. Winding a transformer with a lot of secondary turns without excessive leakage inductance (some converter topologies don't mind leakage inductance, some do).

3. RF getting into the converter and upsetting converter operation.

Is there value to a regulated heater supply? A modern switcher could do this easily. The switcher's current limit could be set to limit inrush current to a safe value.—Peter Traneus Anderson KC1HR; e-mail traneus® emba.uvm.edu

Man White, G3SEK, "Power Protection for

Modern Tetrodes," QEX, Oct 1997, pp 15-26.

Comments About Tetrode Power Supplies

[Here's a dialog between Jerry Johnson, K0CQ, and Ian White, G3SEK, about Ian's QEX article. Jerry's comments are in plain text; Ian's replies are italicized.—Ed.] 0 Nice article Ian. About screen regulation, I see why you've not told all on the reflector—you needed some thunder left for publication.

Well, it was more because I can't cram all the information from 22 pages of typescript and diagrams into one message for the reflector. Also, now that the article is out there, I can refer people to the schematics as well.

I noticed that the circuit using the LM78L12 for reference didn't load it. While my data sheet doesn't require a

0 0

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