[Amps] Glitch resistors

[2]

We buy Ohmite glass-coated/vitreous resistors for glitch service.  They 
are not as tough as high-energy discharge type resistors, but they cost 
Much less $$.  A 10-ohm, 10Wer will discharge a 3kV SB-220, TL-922 ps 
without damage.  We used to use cheaper resistors - but they arced 
between turns, blew apart, and threw schrapnel about during a glitch.  My 
guess is that glass-coating improves the insulating ability from turn to 
turn during a major fault.  For more than 3kV, two or more such resistors 
in series will do the job.  For a higher amount of joules [C >30uF], 
additional units are needed.  //  If you need some of these resistors, we 
sell them for $1.50 each.  To order, send adr, we send parts, pay from 
invoice.  Shipping is $1.00.  //  Also, mfg V-ratings on power resistors 
are usually the case to ground V-rating, not the end-to-end V-rating for 
glitch duty.  The only test for such a resistor is the big screwdriver 
short to ground test -- i.e., if there is no subsequent physical damage, 
the resistor is up to the job.  If one finds damage, go with additional 
units in series.  

cheerz, Pete.

>Has anyone had any experience using Vishay Type RH metal-cased wire-wound 
>resistors (for example Mouser p. 205) as glitch resistors?  There is no 
>voltage rating given, and I'm skeptical about flashover between the 
>windings and the metal case at 2500V and up.  What about the Vishay HL 
>silicone wirewounds ( see Mouser p. 204)?  They seem like a much more 
>conventional choice.  Price is right for both, as is range of values 
>available.
>
>73, Pete N4ZR
>Sometimes a tower is just a tower
>
>
>
>
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-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, 
www.vcnet.com/measures.  
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