how long is the pulse. I learned yesterday we use spools of RG220 to
get a 1.6 usec pulse to fire a kicker magnet in a storage ring.
73
Rob
K5UJ
On Wed, Feb 29, 2012 at 7:19 PM, John Lyles <jtml@losalamos.com> wrote:
> For the big power supply for my TH628 amplifier, 28 kV with 225 uF, do not
> use a high power bleeder. It is a pulsed amplifier, so we need all the
> current we can get, during each mS long pulse. There is a slow trickle
> bleeder (meter multiplier) along with capacitor leakage current, which can
> take a long time to discharge.
> The normal bleed down is a string of very long Carborundum 2 K resistors in
> series, dropped by a big Ross HV relay across the terminals, followed a
> couple seconds later by another Ross HV relay that is a hard short to ground.
> Then, to open the door, there are additional switches as well as big long
> chicken sticks that are used to touch the output. Along with this goes a
> mountain of paperwork and training to satisfy even OSHA. The relay timing is
> all done automatically, so as not to drop before the HV charging supply is
> off. Reverse is true on turn on.
>
> 73
> John
> K5PRO
>
>> Message: 1
>> Date: Wed, 29 Feb 2012 16:03:45 +0200
>> From: "Alf Pousar" <alf.pousar@surffi.net>
>> Subject: [Amps] Bleeders
>> To: <Amps@contesting.com>
>> Message-ID: <F6EDB8E3CF3845EFB10119AC490846E9@fast>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Why not skip the bleeder entirely, and make a current discharge circuitry
>> when the session is over.
>> If the anode voltage is very high then stack some thyristors and fire them
>> with opto couplers.
>> So when you hit the big switch it turns off all power to the power supply,
>> except for the auxillary
>> circuit that keeps the draining alive and then shut off .
>> Not very compicated to do and you get rid of the bleeder heat.
>> Alf OH2QM
>
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