[Amps] Shorting Sticks

Sun Apr 24 20:40:40 EDT 2005

On Apr 24, 2005, at 2:26 PM, Bill Coleman N2BC wrote:

> It won't get warm at all if it's open...

What will prevent the open from arcing?
>
>
> ----- Original Message ----- From: "R; Measures" <r at somis.org>
> To: "Bill Coleman N2BC" <n2bc at stny.rr.com>
> Sent: Sunday, April 24, 2005 5:18 PM
> Subject: Re: [Amps] Shorting Sticks
>
>
> A typical value for a current limiter resistor in a shorting stick is
> 400 - 1000-ohms, 100w.  Discharging even 200J barely gets a 100w
> resistor warm.
>
> On Apr 24, 2005, at 1:52 PM, 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.
>
> Agreed, but if the I-limiter resistor is open, there would be a
> considerable fireworks show.
>>
>>
>> ----- Original Message -----
>> From: "Will Matney" <craxd1 at ezwv.com>
>> To: <amps at 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 at 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 at 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
>>>>
>>>> _______________________________________________
>>>> Amps mailing list
>>>> Amps at contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>> __________________________________________________
>>> Do You Yahoo!?
>>> Tired of spam?  Yahoo! Mail has the best spam protection around
>>> http://mail.yahoo.com
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>>
>>
>>
>>
>> ---------------------------------------------------------------------- 
>> - ---------
>>
>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>
>>
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>
>
>
> Rich Measures, 805.386.3734, AG6K, www.somis.org
>
>
>
>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org