When I mentioned earlier that a hi-pot tester should be used I had forgotten
that the ICE units have a coil to ground. A hi-pot tester would do no good
there.
With Polyphaser units there is no coil to ground, only a gas tube. A hi-pot
tester is what Polyphaser recommends for testing their units. In fact they
even sell one for that purpose. It is called FIST.
To test MOVs Polyphaser also recommends the hi-pot tester. It is true that
the normal failure mode is shorted but they can fail open too.
The low current ( a few microamps) from a hi-pot tester will not harm them.
The capacitors (if they are ok) will withstand higher voltages than the
breakdown voltage of the MOVs.
73
Gary K4FMX
> -----Original Message-----
> From: towertalk-bounces@contesting.com [mailto:towertalk-
> bounces@contesting.com] On Behalf Of K8RI on TowerTalk
> Sent: Wednesday, August 09, 2006 12:46 AM
> To: TowerTalk
> Subject: Re: [TowerTalk] Testing ICE arrestors
>
> Test Metal Oxide Varistors (MOVs) at their working potential. Every over
> voltage, even testing, degrades them.
>
> I would caution uses of Polyphasers not to use this method of testing.
>
> Normal MOV failure mode is shorted. If they have failed open it is
> usually
> quite evident.
> MOVs failing open are usually nothing but a pair of leads pointing to
> where
> the MOV had been located.
> You should try standing next to a 50,000 Joule MOV when it lets go. <:-))
>
> Roger Halstead (K8RI and ARRL 40 year Life Member)
> N833R - World's oldest Debonair CD-2
> www.rogerhalstead.com (Use return address from home page)
>
>
> The surge suppressor for ICE rotator controls uses MOVs in parallel with
> capacitors for each lead. Typical failure modes of each is a short
> circuit or low resistance. I wouldn't hi-pot them, either. Energy from
> the hi-pot may cause an MOV to fail if it is applied for too long a time.
>
> 73 de WOØW
>
> Jim McDonald wrote:
>
> >How can one tell if used ICE coax arrestors or 8-conductor control cable
> >arrestors are still good? DC continuity on the center conductor of the
> >coax
> >arrestors? DC continuity of the control cable arrestors? SWR connected
> to
> >a dummy load for the coax arrestors?
> >
> >Jim N7US
> >
> >
> >
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> >
> >
> >
> >
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