Connectors are commonly greased with silicon grease on the threads but not
on 
the center connector.  This only works when you know that the cable system
is 
a completely sealed system such as waveguide and hardline installations.  
Coax is not usually a sealed system because the connectors at each end are

not really airtight. 
If you cannot have a sealed system then the next best thing is to know
what 
is seeping into the cable.  Water is the worst choice here as it will
attack 
the metal in the shield and seriously degrade the cable.  My solution is
to 
spray everything with ACF-50 and I have yet to find something  that reacts

poorly to the oil.  Corrosion X also seems to work well but I use ACF-50 
because I prefer the smell.  Boeshield is not acceptable.  It is
conductive.  

Sand paper and common lead pencils are not acceptable in the presence of
an 
airplane.  Silicon abrasives will encourage cracks to form in aluminum and

carbon can have some interesting effects on hardened steel.  Keep both
away 
from your airplane.  In the rare event that you get good buy on a used
SR-71 
you should also know that cadmium plated fasteners and tools will cause 
titanium to crack.

When I was much younger and a new ham radio operator I tried very hard to 
have good antenna systems with low SWR as was just discussed on the 
newsgroup.  Now after thirty years of fixing radio systems every day I can

tell you that it makes no difference at all.  That advice will seem
contrary 
to most of the opinions so make your own decision on what is best.  

The most important concern in your antenna system is that the antenna be 
connected at all.  A recent posting on a sailplane group described an
antenna 
inside the tailcone pointing to the rear which gave him only a three mile 
range.  From the opposite coast I correctly diagnosed his problem as a
broken 
connection because my sailplane with the same installation hears over 200 
miles with a junky old radio. 

Which brings us to the second most important thing, noise.  The local 
electrical noise level in your airplane is able to reduce  your range by
10 
to 100 times.  The worst antenna SWR will not drop your range by 1/2 which
is 
nothing compared to your local noise generators.  

The next most important problem is location.  My vor antenna is at the 
tailcone which gives noticeable problems on stations located in the
direction 
I am going.  A single antenna on the belly would perform better in this 
application.  

What doesn't matter:  Length.  Anything within 50% of the correct length
will 
work if it is attached to the radio.

Good luck,
Bob Condon
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