[TowerTalk] cleaning aluminum beam elements

[Jim Lux]

TexasRF at aol.com wrote:
> I am quite concerned about all the aluminum cleaning chat recently. It is  
> well known that any of these abrasive cleaners and pads will leave  
> micro-scratches in the aluminum surface. 

Sure, but all those scratches will rapidly reoxidize.  There is an issue 
of little particles of iron stay behind.


Due to the skin effect at our high  frequencies,
> the rf flow will encounter a maze of conduction channels that not  only will 
> increase the electrical length of the element, can reverse the  electron flow, 
> creating pattern nulls in some directions.

Whoa there pardner.. lots of stuff in those statements, most of which is 
bogus.

1) maze of conduction channels.. possibly, but, as noted above, once the 
surface reoxidizes (in a matter of seconds/minutes) it's no different 
than any other rough surfaced conductor.

2) Rough surfaces won't increase electrical length.  (if you think it 
will, propose some physical mechanism by which this might occur)

3) reverse electron flow?  A couple issues.  it's pretty well known that 
current flow isn't electron flow (the electrons move pretty slowly, 
compared to the speed of light.  I can't conceive of a surface treatment 
that would reverse the current (or electron flow) in localized areas. 
And if there were localized bits that went backwards, it's not going to 
create pattern nulls.


>  
> The only approved method of restoring beam antenna appearance and  
> performance is replacement of the aluminum tubing. 

Indeed, your manufacturer may not approve of scrubbing up those elements 
for one reason or another, which might have an effect on warranty 
replacements, but I suspect that anyone polishing their antenna is well 
out of warranty.


>  
> You can find a complete selection of NEW virgin aluminum tubing at great  
> prices at _www.texastowers.com_ (http://www.texastowers.com)  under the  heading 
> "aluminum". With these low prices and availability, there is no reason  to 
> even think about any other restoration method. Who wants to be caught  scrubbing 
> aluminum when you could be hamming it up instead?!


I would agree that replacing tubing is preferable, and easier if the 
original tubing is really thrashed, however for someone who has some 
spare time on their hands and wants to clean up surface crud on an 
antenna before selling it, storing it, or just putting it up after it's 
been lying out in the weeds, a bit of casual work with a scrubby sponge 
isn't a bad thing.  The suggestion for liquid electrolyte replacement 
while doing the work will make it seem to go faster.  If you're looking 
for that optical mirror polish, well...