Kelly:
Too late to help me at the time, but after I had installed my trbander
with telescoping elements, I found a couple of brass brushes that I'll use the
next time I need to telescope aluminum tubing. I found them in the plumbing
section of Home Despot. They're used to clean out copper pipe. I believe I
bought one half-inch and one three-quarters inch in diameter. Other folks on
TT have suggested a gun shop might have similar brushes for cleaning rifle and
shotgun barrels. You might have to chuck these brushes in a drill and run them
at moderate speed to get out the gunk you described.
When you do get the stuff cleaned out, you ought to use a clean
Scotchbrite pad to clean out any dust and residue from this power cleaning. I
wrapped a piece of Scotchbrite around a large screwdriver blade and rammed and
twisted it inside the tubing. Then apply a thin layer of NoAlOx or similar
compound with a second CLEAN piece of Scotchbrite. Don't use the same first
piece as that now has dust particles on it from the original cleaning. Do the
same (two applications of Scotchbrite and elbow grease) to the outside of the
smaller tubing along with NoAlOx. The pieces should telescope nicely and there
should be no oozing of NoAlOx from the joint. If so, clean it off and try
again.
Also, I grounded the parasitic elements of this same Yagi (actually, a
Bencher Skyhawk) to provide greater capacitive loading for my tower's shunt
feed on 160M. Another reason to short these elements would be to prevent
arcing of same while using the Yagi as top loading for QRO operation.
73 de
Gene Smar AD3F
-------------- Original message ----------------------
From: Kelly Jones <kelly@dxcentral.com>
> Hi TTers,
>
> I have a Cushcraft XM240 that I think has developed an intermittent loose
> connection. I bought this antenna used and put it up this past fall. What
> I noticed is that the person that owned it before me must have used some
> type of "goop" inside the element tubings. The only thing I can assume is
> that it was some type of stuff to keep the tubing joints in good contact
> with each other. On the joints I took apart, I completely cleaned the
> outside of each smaller tube as it slid into the other. However, I had a
> difficult time cleaning the inside of the larger tube that the smaller slid
> into. This was some really nasty stuff and took a boat load of elbow
> grease and sandpaper (yes, sandpaper) to get the elements cleaned up. This
> stuff was really sticky and had all kinds of crud that have accumulated
> over time. The stickiness is what caused me the most problem with getting
> inside the tubes. Steel wool, fine grit sandpaper, etc. all would just go
> in and stick, probably causing more bad than good.
>
> Well, needless to say I think some of that junk is now causing me
> problems. I seem to have an intermittent where my SWR will go high, then
> back to normal, then high, etc. I'm suspecting that there is an element
> that has a piece of tubing that's not making good contact at one of the
> joints. So my question is, does anybody have a way to clean out the
> insides of the tubing sections. I'm obviously going to have to take the
> antenna down to fix it (in the middle of the Colorado winter!) and I want
> to be sure I don't have to do this again.
>
> Also, I seem to recall some talk flying around with regards grounding the
> reflector to the boom with a strap. Can somebody point out the reason for
> this? And finally, what's the consensus of using an MFJ86 (or whatever the
> number is) balun versus a coax wound balun? I have an older W2AU (I think)
> balun that I'm toying with replacing the MFJ with, but am now thinking
> about just making a coax one. Thoughts on this?
>
>
> 73
> Kelly - N0VD
>
>
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