> >> When we did that we could hear virtuallu hundreds
> >> of relays clickking off held by residual magnetism.
Well he "says" it was residual magnetism. I guess we have to
believe somehow he knows that's what it was, and not weak
springs or other mechanical problems.
> >Mechanical non-mercury wetted relays in a telephone switching
> >system?
> >
> >What a system. No wonder the materials in the relay magnetic
> >parts were poor!
> >
> ? ''poor''? All relay armatures contain iron. Hello. If the spring
> isn't strong enough, it can hang up. >........
That's right. With a weak enough spring, the relay won't have any
return force.
But if the iron is soft it should also have no flux storage. If it does
have flux storage, it would take a damn big hammer to
"demagnetize" the metals in the relay.
I haven't seen ANY amplifier relays stick from "residual
magnetism". I suspect the most common flaws...dirt or other
contaminants....contact welding from hot switching...are written off
to "sticking relays from residual magnetism".
I'm not saying it can't happen, just if the iron is too hard the relay is
toast. It will immediately fail over and over again.
Magnetic flux isn't something that accumulates like pennies in a
savings account.
73, Tom W8JI
w8ji@contesting.com
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|