I think you all have valid points and a simple combination of your
suggestions will satisfy everyone.
Place Rich's 1000 ohm resistor in the supply with one end connected to
the HV supply in a position so that you can use that shorting stick to
ATTEMPT discharging the supply through the other end of the resistor
BEFORE using it to short the HV supply directly. ALWAYS, ALWAYS short
the HV supply directly. If the 1k resistor worked, nothing happens, if
it didn't, you save your life even if you do destroy the IG meter,
resistor or both.
I agree with Bill, never, NEVER put anything in series with the shorting
stick. Mine is large stranded cable straight to ground from the hook on
the end of the insulated handle. It will easily handle a huge surge to
ground.
73, Tony W4ZT
Bill Coleman N2BC wrote:
> As one that has literally come across an open 225W bleeder.... I would never
> trust a resistor in series with the shorting stick. If the caps are
> charged, something has already failed. If the caps get damaged, too bad. I
> would rather kill a few bucks worth of parts than me.
>
> 73, Bill N2BC
>
> PS: It's a good idea to routinely test the shorting stick too.
>
>
> ----- Original Message -----
> From: "Will Matney" <craxd1@ezwv.com>
> To: <amps@contesting.com>
> Sent: Sunday, April 24, 2005 4:20 PM
> Subject: Re: [Amps] Shorting Sticks
>
>
> John,
>
> Your saying that a dead-short, quick discharge of a capacitor bank wont be
> rough on the capacitors?
>
> I think everyone knows it to discharge them for safety, but why take a chace
> on the capacitors being damaged on top of it? I can wait 2-3 seconds before
> I do any work, and that's about all it takes. Henry spoke of that Gates
> supply, and I'll about bet they woundn't take a chance on those capacitors
> shorting them to ground, and that being they do use a resistor bank for the
> purpose. Especially over the cost of the capacitors. I think one can still
> be safe and not cost them extra in parts.
>
> Best,
>
> Will
>
> *********** REPLY SEPARATOR ***********
>
> On 4/24/05 at 12:36 PM John Irwin wrote:
>
>
>>I THINK YOU DUDES ARE MISSING THE FOREST>>>>>>>>>>>
>>
>>The purpose of the SHORTING STICK is to KILL THE HIGH VOLTAGE INSTEAD OF
>>YOU!
>>
>>The shorting stick will only damage something is it has already failed or
>>left been left on
>> BY ACCIDENT.
>>
>>ie A bleeder that goes open with no warning. a plate supply powered ,and
>>you forgot to turn it off etc......It protects you. so what if something
>>dies on the power supply>>> You didn't<<
>>You also don't want any other resistors,bleeders,relays or any other junk
>>connected to the shorting stick. just a hook ,10 gage wire and a
>>alligator clip to ground, stick should be about a foot and a half long.
>>
>>The habit of hooking the shorting stick on the hv line may save your
>>relatives pain,and your life,but only if you do it as practice each and
>>every time! First thing done. Last thing removed
>>
>>john kb9tc
>>
>>
>>
>>
>>Will Matney <craxd1@ezwv.com> wrote:
>>Perzactly! My reasoning on the discharger was to allow the caps to
>>discharge through some resistance at first to limit the current, and after
>>a short time, say 2 seconds, a dead short by a relay would finish it off.
>>To me, the quick discharge of a capacitor is really hard on it and can
>>ruining the dialectric.
>>
>>Another thing I dont trust are those safety latches on most amps which
>>mostly short the caps to ground if the lid is opened. Lets say the contact
>>was made once under a full charge, or worse, while the amp was running.
>>Then an arc would burn the contact surface maybe to a complete open. This
>>then could make a high resistance there or even make it fail in the future
>>to where it wouldn't discharge them at all. Next, some poor un-assuming
>>soul went ahead and put his hands on a fully charged capacitor bank
>>(providing the resistors was bad).
>>
>>One rule I always do on a charged capacitor bank or a running amp is to
>>keep one hand behind my back and use the other to do any measurements.
>>This way if I slip, the worse case would be to just get it maybe from a
>>finger to the wrist, across the fingers, etc., and not through my body.
>>Just that shock to the hand is enough to knock the dickens outta ya really
>>quick! One trough the body though could stop your heart! I've been bit
>>before it it sure aint no fun.......
>>
>>Best,
>>
>>Will
>>
>>*********** REPLY SEPARATOR ***********
>>
>>On 4/24/05 at 10:20 AM R@contesting.com;Measures wrote:
>>
>>
>>>A 0½ (zero-ohm) shorting stick can damage an amplifier since there is
>>>virtually nothing to limit peak discharge current. If a 1000-ohm or
>>>so, 100 to 225 watt resistor is added in series with the shorting stick
>>>to limit current, there is less chance of damage.
>>>
>>>
>>>Rich Measures, 805.386.3734, AG6K, www.somis.org
>>>
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>>
>>
>>
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