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Re: [Amps] Zero Crossing circuit

To: jeff millar <wa1hco@adelphia.net>
Subject: Re: [Amps] Zero Crossing circuit
From: R.Measures <r@somis.org>
Date: Thu, 18 Nov 2004 01:57:24 -0800
List-post: <mailto:amps@contesting.com>

On Nov 17, 2004, at 5:03 PM, jeff millar wrote:


Ed...

I've used zero voltage switched solid state relays twice in 2KW amplifiers, one at 432 and one at 144 MHz. The 432 amp included the normal step start circuit, but once I noticed that the zero voltage switching feature, I tried it without a step start in the 144 amp. The circuit switched on with very little drama, the lights blinked about the same amount as when transmitting at full power.

One design note on high voltage power supplies suggested that extremely high surge currents can damage electrolytic capacitors. These surge current maximizes when the turn on relay or switch happens to make contact at the peak of the line cycle. The zero voltage switching function reduces the surge currents to approximately the same amount as what it takes to recharge the caps at the peak of the line cycle.

Free, unsolicited advice: Measure the peak mains-I in both situations with an oscilloscope before assuming that this statement as valid.


...
Richard L. Measures, AG6K, 805.386.3734. www.somis.org

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