| Earls Antenna Work and Experiments NOTE: in Canada ..the official title for the ham radio service is "Amateur Experimental Service" - Amateur Radio people have a long history of technical experimentation and dedication to finding new and improved ways of communications through technical development and experimentation. |
MY R7 (no radials) vertical experiment..look at the R7 prototype below. I
lashed it to the back of my truck in the yard and used it as a temporary Field
Day Antenna. It is a monobander for 20 meters!!! MORE DETAILS CAN BE
FOUND ON MY R7 PAGES CLICK HERE
lashed it to the back of my truck in the yard and used it as a temporary Field
Day Antenna. It is a monobander for 20 meters!!! MORE DETAILS CAN BE
FOUND ON MY R7 PAGES CLICK HERE
This antenna had a very wide
bandwidth.
It holds promise as a wide band
antenna covering more than one
band of frequencies ie..a version
built for 17 meters might cover 14
mhz as well if the conductor was
made somewhat "fat".
I plan to rebuild this antenna some
day.
I think it might be useful to cover
both
20 meters and 17 meters if built
properly.
I would optimize it for
17 meters though..because I don't
have an antenna for that band.
If I had the real estate and the
aluminum and the time..I would try
and build a scaled version for 80 or
even 160 (with inductors).
I think this vertical for 80 would
cover the whole band with low swr
and would elimate the need for all
those radials.
The R7 black box would have to be
modified. The static eliminating
resistor
(rfc) would have to be a larger
inductance for one thing. It could be
done!
It's possible that a "black box"
circuit could be built with ordinary
off the shelf components. Possibly a
4 to 1 commercial balun.
The 50 pf capacitor could be a
variable capacitor to allow some
tweaking . I think the R3 or R4
vertical that Cushcraft first
produced years ago had a variable
capacitor in it.
bandwidth.
It holds promise as a wide band
antenna covering more than one
band of frequencies ie..a version
built for 17 meters might cover 14
mhz as well if the conductor was
made somewhat "fat".
I plan to rebuild this antenna some
day.
I think it might be useful to cover
both
20 meters and 17 meters if built
properly.
I would optimize it for
17 meters though..because I don't
have an antenna for that band.
If I had the real estate and the
aluminum and the time..I would try
and build a scaled version for 80 or
even 160 (with inductors).
I think this vertical for 80 would
cover the whole band with low swr
and would elimate the need for all
those radials.
The R7 black box would have to be
modified. The static eliminating
resistor
(rfc) would have to be a larger
inductance for one thing. It could be
done!
It's possible that a "black box"
circuit could be built with ordinary
off the shelf components. Possibly a
4 to 1 commercial balun.
The 50 pf capacitor could be a
variable capacitor to allow some
tweaking . I think the R3 or R4
vertical that Cushcraft first
produced years ago had a variable
capacitor in it.
BELOW is a simple inverted L antenna. It
worked quite well for me. I took the inverted L
down when
I installed my little mini beam on the tower.
worked quite well for me. I took the inverted L
down when
I installed my little mini beam on the tower.
| THE CUSHCRAFT BLACK BOX IS A VERY INTERESTING CIRCUIT. A FELLOW HAM..Ei7BA ON HIS WEB SITE DISCUSSES IT FURTHUR ..AND IN FACT..HE ACTUALLY BUILDS ONE FROM SCRATCH. I "think" THE R7 IS SOMETHING LIKE A VERTICAL WINDOM STYLE ANTENNA. IF YOU LOOK ON E HAM REVIEWS (A VERY USEFUL SITE) you can see various reviews of these "no radials" verticals such as the R7, R8 and R6000. |
When I put up my little TGM mini beam antenna (20,15,10,6 and 2 meters); my inverted L got taken down.
The "almost wireless" solution to
radiating a signal on 80 meters!!
This year..we got SNOW early and
I didn't get a chance to put up a
proper wire antenna for the low
bands.
What I did do..was I just
connected up a piece of wire to
the tower ..reaching up about 7 ft
from the ground and I feed the
tower directly with this slant wire
feed.
It seems to be working on 80
meters. I feed it as a random wire
with my tuner.
radiating a signal on 80 meters!!
This year..we got SNOW early and
I didn't get a chance to put up a
proper wire antenna for the low
bands.
What I did do..was I just
connected up a piece of wire to
the tower ..reaching up about 7 ft
from the ground and I feed the
tower directly with this slant wire
feed.
It seems to be working on 80
meters. I feed it as a random wire
with my tuner.
I plan to do more work and testing with this simple antenna.
If I use some 9 ft steel cb whips to extend the upper length of the tower..that
might buy me some more effective height of my tower/
vertical antenna. I'm a little worried about lightning so close to the house though!
A better ground system would make for more a more efficient radiator as well.
This type of idea of tapping a metal tower or structure up from ground point and
then feeding it with a tuner as a random wire/antenna could be used on field day!
Imagine tapping onto a big suspension bridge or something or a metal flagpole
outside a building.
If I use some 9 ft steel cb whips to extend the upper length of the tower..that
might buy me some more effective height of my tower/
vertical antenna. I'm a little worried about lightning so close to the house though!
A better ground system would make for more a more efficient radiator as well.
This type of idea of tapping a metal tower or structure up from ground point and
then feeding it with a tuner as a random wire/antenna could be used on field day!
Imagine tapping onto a big suspension bridge or something or a metal flagpole
outside a building.
I have a big series of antenna pages on my old complicated web pages.
YOu can go there ..but you might need a high speed connection. The link is
found by CLICKING HERE.
YOu can go there ..but you might need a high speed connection. The link is
found by CLICKING HERE.
WARNING: MY R7 PAGES ARE B I G.. AND REQUIRE A HIGH SPEED CONNECTION AND LARGE SCREEN
DISPLAY. ...OR LOTS OF PATIENCE!!!
DISPLAY. ...OR LOTS OF PATIENCE!!!
click here to go back to my SIMPLE HAM RADIO PAGES or just use your browsers
back button to NAVIGATE.
back button to NAVIGATE.
The very "simple" DIRECT TOWER FEED system to get me on the low
bands without any wires strung in the air ( I don't like wires overhead)
bands without any wires strung in the air ( I don't like wires overhead)
The theory is simple. The grounded
tower will be at
zero ohms at the ground level. Up from
the ground level the impedance will be
higher than zero. Up near the top of the
tower where the little mini beam resides,
the impedance will be higher still.
At the 7 ft level..the impedance on 80
meters might be something like
200 ohms (very rough questimate).
Well just hook a wire to that point and
feed it power using a tuner. I use my mfj
tuner right at the shack basement
window.
If you have no antenna for the low
bands..you might want to try this out.
Has good possibility for field
operation...ie Field Day.
How about slant wire feeding a big
suspension bridge?
Warning..dont try this with a hydro tower!
It works and I can work stations on 80
meters now.
update info: (february 08)- I compared
signals with a local ham who was using a
more conventional antenna.
I factored in the fact that I was running
only 50 watts and she ran 100 watts.
I was about 7 db lower in signal strength
on 80 meters over about a 350 mile path.
tower will be at
zero ohms at the ground level. Up from
the ground level the impedance will be
higher than zero. Up near the top of the
tower where the little mini beam resides,
the impedance will be higher still.
At the 7 ft level..the impedance on 80
meters might be something like
200 ohms (very rough questimate).
Well just hook a wire to that point and
feed it power using a tuner. I use my mfj
tuner right at the shack basement
window.
If you have no antenna for the low
bands..you might want to try this out.
Has good possibility for field
operation...ie Field Day.
How about slant wire feeding a big
suspension bridge?
Warning..dont try this with a hydro tower!
It works and I can work stations on 80
meters now.
update info: (february 08)- I compared
signals with a local ham who was using a
more conventional antenna.
I factored in the fact that I was running
only 50 watts and she ran 100 watts.
I was about 7 db lower in signal strength
on 80 meters over about a 350 mile path.
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