On Apr 24, 2005, at 2:34 PM, Tony King - W4ZT wrote:
> 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 the 1k resistor does the job, there will a noticeable spark and
sound. If the resistor is open, it will arc across the opening and
make yet more noise.
> 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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>>
>>
>>
>>
>>
>>
>>
>> ----------------------------------------------------------------------
>> ----------
>>
>>
>>
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>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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