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Re: Here pig pig pig
Again, apologies for the late response, but I'm still catching up on old
posts.
D.C. Cox said:
> Your RF choke was fried because you failed to use varisters before and
> after the filter. They will clip the high level transients before they can
> enter the filter. Also, we usually use a small "hash" choke on the
> transient side of the RF filter to clip the higher level RF spikes before
> varisters and then filtering occurs.
Are you talking about MOV's?!? I can think of two good reasons not to use
MOV's:
#1- they have finite lifetimes in terms of the amount of energy they can
dissipate.
Each surge or spike which "turns on" the MOV shortens it's lifetime to a
degree
dependent on the size of the surge or spike. MOV's are not intended to be
used
for constant spike filtering applications, but to block rare surges in
power-line
protection applications. And even then, they are far from ideal.
#2- they are sacrificial components- when an MOV fails, it fails dramatically.
Just read the so-called "testimonials" in any surge-protector's literature,
they
even admit that their products caught fire, even tho they "protected" the
computer
equipment connected to them. No thanks, I'd just as soon my house didn't burn
down due to my computer equipment being protected. (I use a series mode
surge _blocker_ on my computer equipment)
I know a fellow who used one of the very large, heavy duty Square D service
entrance surge arrestors as part of his RF protection network. Despite
blocking
inductors and snubbers, this unit eventually went up in flames from the spikes
coming back from the coil through the pole pig.
-Gomez
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