[ARC5] Sort of OT - Fuzzy VCs

[Tim]

Hi Jim - I have had problems with whiskers on my GRC-9 tuning capacitor
local osc. section.  Presumably tin from the presumably tin plating of the
capacitor plates.  You may be remembering the photo on my GRC-9 post about
the problem that includes a NASA photo of tin whiskers on a representative
variable cap.  Apparently a "growing" industrial problem with
ROHS-compliant lead free solder.  Lead in the alloy seems to inhibit the
growth.
I found that a micro-duster did not remove them however running a piece of
a business card through each gap cured it.  Maybe just temporary..

Some spooky physics going on in these metals...
The NASA photo at the bottom of this post:
http://www.n6cc.com/angrc-9-radio-set
73, Tim
N6CC

On Sat, Dec 2, 2017 at 5:30 PM, Jim Falls <radio-tuber at att.net> wrote:

> I have a Swan 350, and I have had fits with arcing on the tank VC from Day
> 1. It’s a 350pF Hammarlund-style straight line C unit and spacing is a tad
> wider than a BCB VC.
>
> The consensus on the Swan list was dust. It’d blow it out several times a
> week, filter the air going thru the Final cage, all to no avail.  Zapped
> and hissed like a feral cat after a day or two. Got disgusted. Put it away
> in the garage last year.
>
> Pulled it out yesterday. Under bright light, it appears to have metallic
> whiskers all over the place, especially on the stator plates. That thing
> was clean as a whistle when I put it away. Now it looks like I cleaned it
> with fine steel wool.
>
> I recall someone here or on the milsurp list posting a photo like that,
> but I don’t recall any cure.
>
> Is this “fixable”, or am I SOL?
>
> Jim K6FWT
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