Well, if it is the environment that is doing the cap in, and if you can
dismantle the plates of the cap, you might try bonding a thin sheet of Kapton
to the stator plates. Of course, this assumes there is enough gap to
accommodate .003" to .005" of Kapton. Kapton is a fantastic insulator and can
be found at reasonable cost if you look around.
Just an idea...
Russ W6OHM
--- On Sat, 7/19/08, Jeff Maass <jmaass@k8nd.com> wrote:
> From: Jeff Maass <jmaass@k8nd.com>
> Subject: Re: [Amps] Air variable pitting - repairable?
> To: "'Carl'" <km1h@jeremy.mv.com>, amps@contesting.com
> Date: Saturday, July 19, 2008, 3:18 PM
> Carl (and others who have replied):
>
> Thanks for the suggestions!
>
> The environment at PJ2T, perched on a cliff sitting a few
> feet back and 37 feet above the
> Caribbean Sea, is less than friendly to equipment. The air
> is carrying salt spray, the
> humidity can get high, and insects and small lizards crawl
> into placed we don't want them.
>
> The inherent arcing problem Carl mentions below has
> probably been exacerbated by items 1
> and 2 above, and once it starts, it just keeps getting
> worse.
>
> 73, Jeff K8ND
>
>
> > -----Original Message-----
> > From: Carl [mailto:km1h@jeremy.mv.com]
> > Sent: Saturday, July 19, 2008 5:49 PM
> > To: jmaass@k8nd.com; amps@contesting.com
> > Subject: Re: [Amps] Air variable pitting - repairable?
> >
> > No amount of filing and sanding will completely
> restore that
> > plate to its original mirror finish. Microscopic rough
> edges
> > will be the first place it arcs again.
> >
> > Simply remove the plate and realign the remaining
> plates. One
> > less isnt going to matter much anyway, even on 160
> much less 20.
> >
> > TT has had arcing problems since day one due to the
> > configuration of the Pi L; early caps even used Teflon
> sheets
> > between plates.
> >
> > Carl
> > KM1H
> >
> >
> >
> > ----- Original Message -----
> > From: "Jeff Maass" <jmaass@k8nd.com>
> > To: <amps@contesting.com>
> > Sent: Saturday, July 19, 2008 4:59 PM
> > Subject: [Amps] Air variable pitting - repairable?
> >
> >
> > >
> > > We have a TenTec Titan III at PJ2T which is
> currently
> > unusable because of
> > > serious arcing
> > > on 20 meters. It is so bad that the amp will only
> run 300 watts.
> > >
> > > The problem is clearly in the loading capacitor,
> an air
> > variable. There is
> > > an area on one
> > > of the rotor plates that is burned and broiled so
> badly that it has
> > > fattened up the rotor
> > > and it is nearly coming into contact with the
> stator at the
> > spot where 20
> > > tunes up best.
> > >
> > > Can this be fixed by sanding it down (and perhaps
> coating
> > the plates with
> > > something) or is
> > > this always going to be a "weak spot"
> on the capacitor that
> > will start to
> > > arc again?
> > >
> > > 73, Jeff K8ND
> > >
> > >
> > >
> > > _______________________________________________
> > > Amps mailing list
> > > Amps@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/amps
> > >
> >
> >
>
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