[AMRadio] Shorting stick


Jim Wilhite w5jo at brightok.net
Sat Jun 3 20:15:30 EDT 2006


If one wants to use wood, then go to a lumber yard and get some pine closet 
bar.  It is 1 1/4 inch in diameter and is unpainted.  I wonder what you 
would see if the broomstick didn't have paint on it.

I am sure it would be a bit better, but not much since wood is no good 
without moisture.  It rots.  Wood is not good.  One can find Plexiglas rod 
at hobby stores or large glass places, and that would be better.  Check an 
old ARRL handbook for substance insulation properties and use the highest 
value you can get.  If it isn't number 1 or 2, don't use it on voltages over 
600 volts.  A direct short of some circuits can damage components and you if 
it goes through your arm to ground.  I have seen BC transmitters in a pool 
of water because the roof leaked.  One would not want to stand in a pool of 
water with a wooden stick shorting the HV buss.

As for the resistor, always check a shorting stick that has one before 
relying on it.  Need I say, use an ohmmeter to do the thrick to see if it 
has continuity.  A piece of metal with a strap of some kind will cause you 
to jump across the room if a cap of 4 or more microfarad is charged  to 3 KV 
and suddenly discharged.

Once discharged, strap the HV buss to ground with a metal strap to keep the 
caps from recharging.  The higher the voltage the higher the resistor in the 
stick should be and it should be a power resistor.  If you ever see a spark, 
then check the resistor before using it again.  If you see a spark, then 
check the resistor and short the buss again to see what happens.  I have 
seen bad wirewound resistors out of the box myself, but usually they are the 
slider type and the protective cover is missing.  If you find a bad on, you 
can always return it for warranty.  Yeah Right on NOS, but you can try.

Any time I work on equipment that has HV over 600 volts I check my test 
leads and equipment before opening it to make diagnostic measurements. 
Nothing, I repeat nothing replaces common sense when working around high 
voltage.

If you don't agree with any of this, then develop your own procedure that is 
safe, then follow it religiously.  The "one hand behind the back" premise is 
ok, but remember if you get the other in a compromising place, you can 
damage to it.  Put every tip mentioned in this thread together and make 
yourself safe.

73  Jim
W5JO




> OK, just solved a myth about wet broom sticks being of high resistance. I
> put a highpot to a 3 foot length of a broomstick, at 2200 volts I got the
> alarm. I would not use a broom stick, even covered in black tape. Use a 
> high
> voltage glove if you fool with high voltages, weather it be ground or not.
> Regards,
> Gary...WZ1M





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