[TowerTalk] HF2-V Doorknob Capacitor Failures

[K0FF]

Hi Bill, there is another product similar to RTV in appearance and is
silicone based, but made especially for HV ( and I meanHHv) dielectric. I
used to have a 1 pound can of it somewhere, and if I can find it, will give
more detail. We used it to pot 15KV solid-state powersupplies. Meanwhile I
wonder what Q-Dope or Glyptol would do outside? I'll run a test this winter,
as I use Q-Dope on torroids so there is some handy.
I've always wondered about leaving that capacitor open to freeze-thaw cycles
too.
In my opinion, the HF2V is as good as a "multiband " vertical can get
otherwise.

Geo>K0FF
---Original Message-----
From: Bill Jackson <k9rz@radiks.net>
To: towertalk@contesting.com <towertalk@contesting.com>
Date: Friday, September 22, 2000 6:13 PM
Subject: [TowerTalk] HF2-V Doorknob Capacitor Failures


>
>Towertalkians,
>
>I have a Butternut HF2-V 80/40m vertical that has served me well for over
10
>years.  The only problem I have experienced is the periodic failure of the
200
>pF, 10 kV, door knob capacitor on the 80m coil assembly.  I have had to
replace
>this cap about every 3 years or so.  The failure mode is usually rather
>spectacular, occurring with a loud bang and pieces of the capacitor ending
up
>several feet from the antenna. It appears that maybe moisture is getting
into
>the capacitor causing a flash over which ends up destroying the cap.
>
>I have thought about using some type of sealer on the ends of the cap to
prevent
>the moisture from getting in.  I am hesitant about this as I don't want to
>affect the electrical characteristics of the cap.  Has anyone done this
before
>with any success and if so, what type of sealer did you use?  Someone
suggested
>using RTV, but having learned from towertalk about the acidic properties of
RTV
>type sealant, this doesn't sound like a very good idea.
>
>Any thoughts?
>
>Thanks in advance.
>
>Bill - K9RZ
>
>
>
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