Re: Wire-wound resistors as dummy test load

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<sundog-at-timeship-dot-net>
> 
> Hi All,
> 
>   A note on wire-wound, aluminum cased power resistors...
> 
>   I used some 3kohm, 25w power resistors an the grid-leak resistors in my
> old dual 833A VTTC.  After about 1 minute of operation, the endcap blew out
> explosively (ceramic shrapnel went everywhere), shooting across the garage
> and shattering against the far wall.  The resistor itself was attached to
> the coil's deck with small wood screws, so it stayed in place.
> 
>    Be wary of these resistors.  They don't seem to like having their
> wattage rating exceeded, and complain very loudly by blowing and throwing
> out shrapnel. I think I'll stick to ceramic core wirewound resistors from
> now on :)

	How much grid current were you running?  Any 3k 25W resistor should be
able to handle about 90 mils continuosly, and more if it was tied down
to anything requiring a heat sink.  I've seen WW resistors melt from
overload, but that "blowing out the end caps" is something new.  What
kind of resistors are you using which have end caps?  Daleohms or
equivalent?  Sorta sounds like it.

Ed