[AMPS] SS relay on mains

[Kenneth D. Grimm]

John Lyles wrote:

<stuff snipped>

> It is very dangerous for safety however, and one should always pull
> the
> plug or turn off a physical switch before sticking hands in, due to
> the
> leakage through the relay semiconductor. It will charge up power
> supplys
> very slowly, and will cause nasty shocks (mA or so on some older
> devices,
> depending on the voltage). Can also fail shorted, with obvious
> results...

Couldn't agree more.  When working on a QRO amp, always, always unplug
the unit from the AC line and short the hv to ground using an
appropriately insulated shorting stick.  When looking at some of the
interlocks, and in some cases lack of interlocks, I am amazed that more
of our happy band haven't bitten the dust while attempting to fix their
amps.  My homebrew amps were never equipped with interlocks, but there
was always a shorting bar provided to make sure that everything was
discharged before I stuck my hands ( or anything else) inside the amp.

It is interesting to note that considerable engineering went into the
interlocks on some of the old boat anchor amps like the Johnson Viking
Thunderbolt.  You had to be pretty determined to defeat the interlock on
that hunk of iron.

Ken K4XL
grimm@alison.sbc.edu



--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm