Jerry wrote:
Finally, I have seen screwdrivers mounted on the ladder
in the horizontal facing rearward and high enough to stay
away from other vehicles. Then it was braced with another piece of non
conductive material in that position
OR slanted up towards vertical. This, of course, kept it
out from bridges but let it operate well. Use a stiff upper
whip.

Another idea is to locate the antenna on top of the vehicle and
install a very large top hat one foot above the coil. That would
limit the height of the antenna system to about four feet above
the top of the vehicle. I once tried an experiment of a 6'x14'
piece of 1/4" hardware screen mounted four feet above the cab
of my pickup used as a top hat for my High Sierra screwdriver.
It minimized the amount of coil required and put out one heck
of a signal. Field Strength measurements indicate that it would
have placed at the top in a 75m mobile shootout.

A 6'x14' top hat would actually be easier to implement on an RV
than on a pickup.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

Jerry wrote:
Finally, I have seen screwdrivers mounted on the ladder
in the horizontal facing rearward and high enough to stay
away from other vehicles. Then it was braced with another piece of non
conductive material in that position
OR slanted up towards vertical. This, of course, kept it
out from bridges but let it operate well. Use a stiff upper
whip.

Another idea is to locate the antenna on top of the vehicle and
install a very large top hat one foot above the coil. That would
limit the height of the antenna system to about four feet above
the top of the vehicle. I once tried an experiment of a 6'x14'
piece of 1/4" hardware screen mounted four feet above the cab
of my pickup used as a top hat for my High Sierra screwdriver.
It minimized the amount of coil required and put out one heck
of a signal. Field Strength measurements indicate that it would
have placed at the top in a 75m mobile shootout.

A 6'x14' top hat would actually be easier to implement on an RV
than on a pickup.

I'm not sure i understand what you mean by a top-hat?
Do you thing something like this could be used with the body of the
scredriver antenna mounted horizontally on top of the rv and the Top hat
mounted close but seperately, making the antenna basically flush with the
top of the rv ? If that makes any sense.

--
Registered Linux User #346565

Jeremy Salch wrote:
I'm not sure i understand what you mean by a top-hat?
Do you thing something like this could be used with the body of the
scredriver antenna mounted horizontally on top of the rv and the Top hat
mounted close but seperately, making the antenna basically flush with the
top of the rv ? If that makes any sense.

It would look something like this with a four foot slanted bottom
section:

6'x14' hardward cloth top hat
+---screwdriver coil---+---================================
/ X X X
4' / X X non-conductive supports X
___/_____X______________________X_____________________ _____________X
Top of RV

The highest current would be flowing through the 4' slanted section
which is good. That four foot figure is arbitrary. Make it as tall
as is feasible. If it were me, and the top of the RV is 'z' ft. from
the ground, I would make the base as long as is legal, but that's
just me.

This is similar to a $20 junk box antenna with which I tied a 75m CA
shootout for top honors against top-of-the-line (expensive) bugcatcatchers
and screwdrivers. My loading coil and top hat were horizontal, as above.
My base was an 8 foot whip slanting from my trailer hitch up to an
elevation of about 12 feet above ground.
--
73, Cecil http://www.qsl.net/w5dxp



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