[Amps] Vac Relays for B+
Ian White GM3SEK
gm3sek at ifwtech.co.uk
Sun Feb 7 10:44:51 PST 2010
Gary Schafer wrote:
>> The purpose of a properly sized HV resistor is to both limit a tubes
>>fault current during an arc but to also survive until the primary
>>fuse or breaker does its job. A true vitreous enamel wirewound
>>works well for this.
>> OTOH, that tiny resistor can AND WILL sustain an arc under the right
>> conditions and result in some serious damage to other components.
A genuine purpose-designed HV fuses don't look anything like a small
resistor. That should be telling us something...
>I agree with Carl. A fuse in the high voltage, whether it be a resistor
>or a regular fuse will sustain an arc when it opens and can let more
>energy thru than you want.
>The glitch resistor can not be just any old resistor either. It has to
>withstand the full high voltage potential of the power supply. When
>there is a short, full high voltage appears across the glitch resistor.
>Sometimes more than one vitreous enamel resistors are put in series to
>get the voltage rating needed.
Yes - and Jim VE7RF had it right too:
## The big 50 ohm glitch R.. LIMITS the fault current. The HV fuse,
INTERRUPTS the current !
That's right: two different components, two different functions.
It's all in Eimac Bulletin 17 <http://tinyurl.com/18r>
73 from Ian GM3SEK
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