[TowerTalk] Antenna Grease--Deficiencies and Remedies.

[K7GCO@aol.com]

In a message dated 6/24/00 2:53:49 AM Pacific Daylight Time, k4sqr@juno.com 
writes:<< 
 Tom;
     It's called        P-E-N-E-T-R-O-X- AES and others carry it. 
 
 On Fri, 23 Jun 2000 23:29:15 -0500 (CDT) w4th@webtv.net (Tom Hix W4TH)
 writes:
 > 
 > What is the name of the product many people put on the elements of their
 > beams where they slide together to keep down corrosion and to also 
 > help conductivity. > 
 
 Good luck; 73, Jim Miller, K4SQR,  http://www.comteksystems.com

     I have used as much Penatrox as anyone and will point out some serious 
deficiencies.  It does keep moisture off the aluminum and prevent the 
"Dreaded Aluminum Yagititus".  The zinc particles serve no useful purpose as 
it is a dissimilar metal for starters and if there is any moisture around it 
in the slightest there will be some corrosion.  The goops with aluminum 
particles are the only ones to use like Anti Seize with aluminum particles.  
As far as conductivity enhancement is concerned from even the aluminum 
particles, consider this.  The RF travels on the outside of the tubing and 
the conduction path is right at the diameter change junction only which is 
only a very thin ring or area under a bolt or self taping screw.  So the 
particles of aluminum or zinc between the telecopying area do nothing for 
you--only at the thin ring of conduction.

Further I've had beams that had SWR changes using Penatrox over a period of 
time.  It wasn't supposed to do that I completely cleaned the joints inside 
and out, refreshed the Penatraox and the SWR returned to 1:1. The elements 
did come apart easy however and cad plated bolts don't rust.  I switched to 
SS bolts long time ago but it's a dissimilar metal and without a coating the 
"Dreaded Alumitoid Yagititus" occurs.

A friend used Penetrox and he had a change in performance he noticed. When he 
got the elements apart which required some effort, the Penatrox was so hard 
he had to use a file to get it off on the smaller element and a steel brush 
for the inside of the element.  The goopy base failed over a period of time.  
Silicone grease keeps moisture and air from the surface and never changes.  
I've used it alone with no changes.  I was going to run tests with a HP low 
resistance Ohmmeter but that isn't a fair test.  Any surface that conducts 
inside the joint would help to lower the DC resistance.

I started using the Flea Market Aluminum solder on the joint and created a 
"No Maintenance" joint for the first time.  I cleaned the joints real well, 
spun the tubing in a lathe slowly and applied a Burns O Matic torch.  At a 
certain temperature the solder flowed just like regular solder.  The joints 
are 6 years old and are still perfect.

I was given several 12' elements of 1.5" tubing telescoping into 1.625" 
tubing that had been together for 40 years and "mechanically frozen".  There 
are many yagis out there in this condition.  The small quantity price to buy 
this aluminum was over $1000 and I was determined to salvage it.  I tested it 
with an ohmmeter and the meter would rise and then fall to some value. When 
disconnecting and reconnecting the meter, it rose to the lower level only.  
When I reversed the leads, it repeated the results.  The joint held a charge 
and the Ohmmeter reading was around 200 ohms. This was definitely a 
capacitive joint. The next time I get a joint that bad I'll use and impedance 
meter to measure it.  I understand that aluminum oxide is used in 
electrolytic capacitors and that is the way they act when an ohmmeter is 
applied.

This is one reason I'm switching to quads.  There is one permanently ZERO 
resistance soldered joint per element and replacing wire is 100 times cheaper 
than aluminum if needed.  Quads don't suffer from any electrical 
deterioration.  If properly designed it literally requires no maintenance.  
Take a look at Antenna Marts No Maintenance Quads.  Raibeam supplies Anti 
Seize with aluminum particles goop with it's beams even though it costs more 
than Penatrox.  It's a no maintenance yagi.  The Hex Beam reflector has no 
joints and the DE only has the feedpoint connection right at the mast where 
it could be remade easily.  I use silicone grease on all bolted joints.  

Take your yagi down and apply an ohmmeter to the joints.  Be prepared for a 
shock of an emotional nature.  Clean the joints and coat with a goop with 
aluminum particles.   

I was determined to get these joints apart without the hack saw.  I used the 
"K7GCO Jack Hammer Technique."  I installed an aluminum plug in the end of 
the element secured with 2 bolts. One wasn't enough.  I inserted a 10 lb rod 
in the other end of the element and standing on the edge of the house, I 
raised the end and let this 10 lb rod hit the plug in the end element.  The 
joint wouldn't move.  I almost gave up.  Finally it started to move a bit and 
it took about 100 jack hammer operations to get the joint apart.  I even had 
to jerk the tubing up when it hit.  The aluminum oxide on the outside the 
element had increased the tubing diameter .015" and probably decreased the 
diameter inside the same.  I used a file on the outside and a rotary steel 
brush on a drill motor inside the tubing to remove it.  This was a real 
"Compression Capacitive Joint" which many yagis have.  After a while, SS 
clamps aren't needed if nothing was used on the elements.

Penatrox gets hard and has the wrong particles in it for what ever value they 
might have.  Penatrox was designed for twisted copper wires in the open where 
the area of conduction is full length carrying 60 cycles.  The Particles help 
there but why weren't they particles of copper?  k7gco

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