On Jul 15, 2004, at 3:08 PM, Ian White, G3SEK wrote:
Oleg Skydan wrote:
Hi, All !
On the other hand, for tubes up to the 1500W class, Eimac's and
Rich's
recommendation is a good one:
>> limit I-peak with a suitable HV glitch R and use circuit
breakers, or
>>250v fuses, in the primaries of the PS transformers.
What do you think about switching HV off with the vacuum relay ?
Is it better than fuses/circuit breakers in the primaries of the PS
transformer ?
It doesn't need to be as fast as a vacuum relay. With conventional
mains switching relays and an electronic anode current sensing
circuit, a crowbar short will usually shut down the HV without blowing
any fuses.
•• Ian --- The issue is seemingly to prevent damage to the amplifying
device from the current peak generated by the stored energy in the
filter caps. Would a mechanical relay be fast enough to do this? //
What kind of a crowbar would be able to function in a 9000V power
supply?
The glitch resistor protects the tube against the first current surge
out of the HV capacitor, so there is no great strain on the relay.
•• If the glitch-R protects the tube, we need a HV crowbar to protect
______?
You must always have mains fuses or breakers as well, but hopefully
these will only be a backup.
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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