For possible info on what is in the Watts Unlimited power supply, you might
want to look into the article in QEX a few years ago by W9QQ. The
commercial power supply MAY be similar to the one described in the QEX
article. As I recall, the QEX article described an open loop switcher power
supply design that had 2 KV out at one amp.
73, Harry, W3IIT
At 11:22 AM 3/17/2003 -0500, RFlabnotes@aol.com wrote:
>Recently we all heard about a new HV supply for KW amps, being sold by Watts
>Unlimited. As promised, I contacted them for some inside info, and they were
>very open and co-operative. (More and more I am beginning to realize that the
>only people who are hyper-secretive with basic product info are those who
>don't really know what they are doing, or are overtly scamming.)
>
>This product is called PSA2500 and is the brainchild of Tim, W9QQ, and in my
>opinion he is a very capable power supply designer. I have discussed the
>thing with him offline and his logic for design and marketing of this product
>are FB.
>
>As some of us suspected, it is an open-loop inverter, running at 64KHZ, which
>explains the stated voltage regulation. In reality, it acts pretty much like
>a conventional transformer/rectifier/capacitor supply with regard to
>transient response, and has a healthy amount of C.
>
>The fact that it runs open-loop is very significant from a design standpoint,
>particularly with regard to EMI generation. His basic design topology must,
>unfortunately, run open loop. But that topology has an overwhelming benefit:
>very low HF ripple current on the input. Large supplies like this are
>nightmares to EMI proof. So in order to be able to produce a product that is
>practical, this compromise was accepted. The result is a usable product, and
>more importantly, it can be produced affordably.
>
>In the power supply business, retail prices generally run in the .$.5-1.0 per
>watt range for a 'full-featured' supply. If we had to pay this price, I don't
>think there would be any takers - hence, no suppliers. I say congrats to Tim
>(no, he is not a relative or creditor of mine) for bringing to the ham market
>a product which has practical value and suitable performance.
>
>As a previous participant myself in the power electronics market, I am
>extremely sensitive to reliability of these designs. A serious circuit
>failure frequently leads, in milliseconds, to a handful of expensive MOSFETS
>being reduced to rubble. The mfr. must be prepared to replace these on
>warranteed products, so he better do his homework in the design/testing -
>otherwise any profit is quickly converted into income for the transistor
>mfrs. Let's hope Tim has done his homework. Time will tell.
>
>73
>Eric von Valtier
>
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