On Sun, 9 Jan 2005 19:55:41 -0500, "Jack Painter"
wrote:

The reaction from battery acids, air and dirt are minimized with grease. But
mechanics who grease the inside of the cable-clamp and outside of the
battery post *before the connection is made* are not helping the electrical
connection - they're applying preventative maintenance for idiots - who
never clean their battery posts. Conductive paste is much more expensive
than grease. Those who know what they are doing use the former.

Jack, many thanks for your informative post, it was certainly an
interesting read, and deserves a response.

I'd like to quote what Brian Reay said in reply to another poster on
this topic. He said "If it isn't in the current path (i.e. between the
mating surfaces) and also not acting as an unwanted path (eg between
the earth clamp and the antenna), does it matter? OK, you may get some
local absorption of RF energy, but how much grease are you going to
use? Not enough to absorb much RF and the mass of grease (or vaseline)
will be far less than other unquantified RF conductors and absorbers
in the vicinity.

You need to look at things like this in the context of the problem."

Now I don't doubt that everyone who has contributed is right in their
own way, but look at the wider problems of the Radio Amateur's
vertical antenna that demand attention. Only having one element, it
has to work against something, which in this case is the ground or
earth. To work with some efficiency it has to make good contact with
said ground or earth, and I did some calculations elsewhere showing in
simple terms how this can vary with the ohmage of the earth path.
Hence the advice about radials wires, cost, corrosion, and all the
other things.

But this antenna has to live outside and cope with wind, rain, snow,
ice, hail, frost, dog pee, etc, the whole nine yards, and this has to
be taken into account in the design and construction phases. What you
wind up with is a compromise, and everyone's choices will likely be
different. I doubt that anyone puts up a vertical antenna designed to
cope with a lightning strike - and very many antenna designs (such as
balanced dipoles) might have either no DC earth path or only a
fortuitous one - or even a 1000 ohm resistor as a static leakage
path....it just doesn't feature as a major topic.

Just to illustrate the point about what is incorporated in antenna
designs, we've had some bad weather here in the UK over the last few
days. One amateur on here had his wire doublet aerial anchored in a
tree, which blew over in the wind. It pulled his aerial along,
together with the length of feeder to his radio. Result was everything
on the shelf was pulled off onto the floor. So although this amateur
had an off-the-shelf design of aerial, he had no snap-line in place
that would have broken when the tree went over. I'll bet there wasn't
much lightning protection either.....

It comes down at the end of the day to the art of the possible. While
a storm-proof, lightning-resistant, non-corroding, highly efficient
vertical antenna could be designed and constructed, it would cost a
fortune, and at the end of the day you'd still have 'only' a vertical
antenna - which anyway is not an all-round solution to working other
amateur stations.

I myself had a vertical antenna for some decades, the earth system of
which was constructed along the lines I mentioned elsewhere. It
withstood everything thrown at it, including the 'great storm' of 1987
with hurricane-force winds. On those occasions when licensed amateurs
used it, there was negligible fall-off in the aerial current over its
life-span, which told me that the earth system was not deteriorating.
In the end the 'maintenance' of this aerial consisted of an occasional
spray of WD40 (shock, horror) - but when finally dismantled, *all* the
mating connections were bright and tight....it served me well and I
don't think I could have asked for more.
--
from
Aero Spike