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February 10th 04, 05:28 AM

oUsama (Yuri Blanarovich) wrote in message
The flat earth society will argue that it can be only 0.1 dB improvement, but I saw on average about 7 S-units boost.

Nope. The low 1 db or less figures we tend to harp on is the amount of
modeling error one would likely see. Not related to antenna
improvement by relocating loading coils or addign top loading. I see 2
S units increase on average just from adding the lower 3 ft mast to
mine. "75m" 7 S units is impressive, and fairly believable to me if
the original antenna had a low coil, and no top loading on 160m. That
would tend to indicate you have quite a bit of ground loss to see that
difference. "normal on 160" You have to be real careful when placing
coils and loading wires above sheet metal though. Any sheet metal too
close to the coil or upper whip, and it will totally kill the
performance. I once tried running 2 Vee loading wires from above the
coil, to the front of the car. The antenna was mounted on the trunk
behind the back window. "chevy monte carlo" But it didn't work. The
wires ended up too close to the hood and roof. It might have been ok
if I had a mast on the front of the car to elevate the wires higher
off the car. I sold that car, and now only drive the truck at the
moment. The truck gets the antenna higher overall, but it's more of a
pain because I have an aluminum camper shell on the back. Thats one
reason why I keep the coil well above the roofline...I think it helps
a bit that the antenna is mounted next to a window rather than all
metal.
It only sees a horizontal strip running across, and it's well below
the coil.
I guess your loading wires were far enough away from the body not to
be effected. If it does couple to the body, the antenna will "act"
like it's working, IE: tuning, etc, but will resemble a dummy load
when you try to use it. When I rig up loading wires, I'll run them off
away from the truck to a tree or something. Thats how I currently can
work 160 using my 80-10 antenna. It works fairly well because I'm
using fairly few turns of coil, and a pretty long loading wire. Takes
like 25-30 ft or so if I remember right.
MK