Dave Edwards kd2e at comcast.net
Wed Aug 17 14:56:14 EDT 2005

Uh....couldn't 'ya get another knob from TT?
----- Original Message ----- 
From: "Ed Worst" <edworst at att.net>
To: "TenTec Contesting" <tentec at contesting.com>; "TenTec List" 
<Tentec at mailman.qth.net>
Sent: Wednesday, August 17, 2005 2:37 PM
Subject: [TenTec] MUSHY KNOBS

> I've noticed for some time that some of the switches on my TenTec gear 
> seem
> to be, well, mushy.  The Mode Switch and the Band Switch are especially
> prone to this.
> It turns out it's the knob, not the switch, and the problem is that if you
> overtighten the setscrew, the inner circle of the knob cracks and doesn't
> maintain a firm grip on the shaft.  Take one of those knobs off and look 
> at
> the underside and you'll see what I mean.  There's a circular gap between
> the inner circle which fits the shaft and the outer circle which is where
> the body of the knob begins.  (Seems like a poor design, given the 
> function
> of the knob.)
> I thought that if I filled in that gap in the knob, it would make the knob
> solid and less likely to crack when the setscrew is tightened.  So I tried
> some J-B WELD as filler, and it worked.  First, I had to restore the inner
> ring to its original position.  This was done with a flat wooden 
> toothpick,
> but other items will work also.  Just don't plan on re-using this spacer
> because it'll become a permanent part of the repair.  Mix about a 1 inch
> stripe of Part A and Part B of the J-B WELD together, and carefully fill 
> in
> the gap.  The J-B WELD has the consistency of toothpaste, so you'll have 
> to
> work it down into the gap.  I used another flat toothpick to do this. 
> Wipe
> off any stray epoxy before it sets.  The package recommends a 15 hr cure
> time, and I'd recommend following this recommendation.  The last thing you
> want is to apply any stress to the epoxy before it's fully cured.  By the
> way, I chose J.B. Weld because it seems to be readily available at any
> autoparts store, and also because the description on the package states, 
> in
> part, "The city of Dallas, Texas repaired a cracked Caterpillar engine 
> block
> with J-B WELD and saved $4,000.00 plus 30 days down time."  If it's good
> enough for that, it should be good enough for plastic knobs.
> So, if you have this "mushy knob" problem, give J-B WELD a try.  It works
> for me.
> 73,
> ed - k9ew
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