If I could add my "two cents" to this discussion. Any ham who has the
slightest thought that a large oil filled capacitor is charged should bleed
the voltage to ground through a 100K resistor, acting as a bleeder
resistor.
By the way, be very careful not to assume that your bleeder resistor is
functional. Lots of folks, including myself, got nipped by a bleeder that
opened up! Thank goodness it was only a few hundred volts but what if ....
A shorting stick should be in evey hamshack. The one that I have is made
from a phenolic rod about a foot long with a insulated copper braid with a
clip attached to a hook rod at one end that I drape over the filter
capacitors when working on the amplifier. It was issued to me when I was in
the Air Force working on 5 KW transmitters. If the sergeant saw you without
your "Jesus stick" you might get your butt kicked.
Crazy story: I had a friend who used to charge up a 100 mfd/4000 volt oil
filled capacitor to see how long it would stay charged!! He wasn't too
bright.
Dave, W3ST
Publisher of the Collins Journal
Secretary to the Collins Radio Association
www.collinsra.com - the CRA Website
Now with PayPal
CRA Nets: 3805 Khz every Monday at 8 PM EST
and 14255 every Saturday at 12 Noon EST
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <amradio@mailman.qth.net>
Sent: Monday, June 05, 2006 9:42 AM
Subject: Re: [AMRadio] ground sticks again
In a message dated 6/5/2006 0:25:48 AM Eastern Daylight Time,
[EMAIL PROTECTED] writes:
it can ruin the capacitors with excessive
instantaneous current surges. Better to first discharge through a
resistance to limit the discharging current, then apply the "coup de
grace"
by shorting directly.
How do you intend to handle the resistor while doing the discharging? You
are
still going to need a shorting stick. If the initial charge opens the
resistor, tyou are still going to have a huge discharge when tou roun the
cap
directly. It is much better to take the slight chance of discharging the
cap the
direct way than messing around with some Rube Goldberg resistor
arrangement. If
the Great Electron Gods had intended for capacitors to be discharged
through a
resistor (other than a bleeder) before working on a circuit, them he would
have made discharge sticks with built in resistors. I have never seen one,
have
you?
Transmitting caps are not that hard to find, not that expensive. You can
find them at nearly every hamfest. At the Manassas, VA hamfest yesterday,
there
were 2 large piles of them at one vendor in the flea market and he would
almost
pay you to take them home.
73,
John, W4AWM
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