| MOTORIZED (with a cordless screwdriver motor) 17 foot high BASE station Vertical for the backyard. |
The 17 foot vertical in the backyard. There is a buried counterpoise under
this antenna. It is motorized and can be adjusted to any frequency from 18
mhz down to 3.5 mhz. For 160 meters, another coil and whip can be put
into service so TOP BAND can also be covered for when I want to work
contests or certain events.
this antenna. It is motorized and can be adjusted to any frequency from 18
mhz down to 3.5 mhz. For 160 meters, another coil and whip can be put
into service so TOP BAND can also be covered for when I want to work
contests or certain events.
The cordless screwdriver was taken apart. The switch on the case was
removed. The rectangular hole will allow the new nr 14 guage remote
power line to attach to the terminals on the back of the motor.
The Screwdriver case was cut with a jig saw. I sawed off about 2.5
inches of the handle. The yellow tape keeps the motor and gear
assembly locked together. Lots of vinyl tape was used in this early
model. I taped assemblies of parts together and I will use the antenna
and make refinements and changes and smooth out the rough edges of
this project as I go along.
removed. The rectangular hole will allow the new nr 14 guage remote
power line to attach to the terminals on the back of the motor.
The Screwdriver case was cut with a jig saw. I sawed off about 2.5
inches of the handle. The yellow tape keeps the motor and gear
assembly locked together. Lots of vinyl tape was used in this early
model. I taped assemblies of parts together and I will use the antenna
and make refinements and changes and smooth out the rough edges of
this project as I go along.
The power line is 2 lengths of nr 14 guage insulated stranded wire. I twisted the pair together using a hand drill outside. Most of the handle of the cordless
screwdriver was cut off. A fiberglass support pole will mate up with the cut end and it will be held together with a good solid wrapping of electrical tape. It would
not be a bad idea to put a few bypass capacitors at the DC input to the motor. I left some pigtails in place and I may do that later on. The nice thing about antenna
projects is you can use them for awhile and then tweak them, modify them, and tinker with them. With a ground mounted vertical..it is a fairly easy thing to do. No
tower climbing or complex assemblies.
I know when I read the original Don Johnson W6AAQ instructions..they did seem a bit mechanically complex. When I finally got around to assembling this antenna,
it was fairly easy. I added my own wrinkles and I made things simple..at least for now at the start of the project. It works and I feel a sense of accomplishment and
that is what counts. The taped mechanical (kind of a lash up..really) connections..work! They dont show ..because they are on the inside of the vertical radiator!
The hardest mechanical part is the coil. I dont have a lathe. Ernie Jury, VE3EJJ actually made the coil on his lathe and we both were going to build this project at
one time.
screwdriver was cut off. A fiberglass support pole will mate up with the cut end and it will be held together with a good solid wrapping of electrical tape. It would
not be a bad idea to put a few bypass capacitors at the DC input to the motor. I left some pigtails in place and I may do that later on. The nice thing about antenna
projects is you can use them for awhile and then tweak them, modify them, and tinker with them. With a ground mounted vertical..it is a fairly easy thing to do. No
tower climbing or complex assemblies.
I know when I read the original Don Johnson W6AAQ instructions..they did seem a bit mechanically complex. When I finally got around to assembling this antenna,
it was fairly easy. I added my own wrinkles and I made things simple..at least for now at the start of the project. It works and I feel a sense of accomplishment and
that is what counts. The taped mechanical (kind of a lash up..really) connections..work! They dont show ..because they are on the inside of the vertical radiator!
The hardest mechanical part is the coil. I dont have a lathe. Ernie Jury, VE3EJJ actually made the coil on his lathe and we both were going to build this project at
one time.
This version I cobbled together with left over antenna parts. The fiberglass pole (from lightning bolt quad). You could use a fiberglass pole from a
hardware store. The type that is used to hold a saw or pruning aid for tree branch trimming. The length has to be adjustable (two pieces of fiberglass pole
that slide into each other. That way you can get the right length through trial and error so that one end of the fiberglass pole holds the screwdriver motor
at the right spot in the vertical pipe and the other end of the fiberglass pole sticks out the far end and is part of the base insulator.
hardware store. The type that is used to hold a saw or pruning aid for tree branch trimming. The length has to be adjustable (two pieces of fiberglass pole
that slide into each other. That way you can get the right length through trial and error so that one end of the fiberglass pole holds the screwdriver motor
at the right spot in the vertical pipe and the other end of the fiberglass pole sticks out the far end and is part of the base insulator.
Some of the assemblies I was working on today..Oct 9 2011. I lay them
temporarily on my ATV and boat as I was figuring out the dimensions and working
on the couplings ect.
The 12 foot 2 inch diameter copper pipe is the main part of the vertical radiator.
At the top is a coupling for 2 inch copper pipe and that was used to hold the
fingerstock. I soldered the finger stock to the pipe coupling.
I did all the soldering outdoors. The fingerstock is berillium copper and you dont
want to breath in the dust or fumes from it being heated when soldered.
The pvc coil with a 4 ft small diameter aluminum tube is shown here.
The aluminum tube is not solidly connected to the pvc coil form. I am going to
make a proper rigid coupling in the next day or so.
temporarily on my ATV and boat as I was figuring out the dimensions and working
on the couplings ect.
The 12 foot 2 inch diameter copper pipe is the main part of the vertical radiator.
At the top is a coupling for 2 inch copper pipe and that was used to hold the
fingerstock. I soldered the finger stock to the pipe coupling.
I did all the soldering outdoors. The fingerstock is berillium copper and you dont
want to breath in the dust or fumes from it being heated when soldered.
The pvc coil with a 4 ft small diameter aluminum tube is shown here.
The aluminum tube is not solidly connected to the pvc coil form. I am going to
make a proper rigid coupling in the next day or so.
Using a hand grinder, I formed the end of a screwdriver bit so
that it would fit snuggly into the coupling shown here.
that it would fit snuggly into the coupling shown here.
Base of the vertical with coax connection. You can see the
other end of the fiberglass pole assembly ..just peeping out of
the base and acting like an insulator at the base.
Right now..it is just held there in place with electrical tape. In
the next few days..I will be making a much more solid
arrangement than this.
FUTURE REFINEMENTS: 1) lubricate the threaded rod to
prevent corrosion. I am thinking of using a synthetic bicycle
chain open air grease.
2) Paint the 12 foot copper pole. Im thinking of basic black or
grey.
3) Try and order a Lexan clear plastic tube for the coil cover.
Right now..I am using a simple clear plastic map case. It is
sitting a wee bit crooked on the pipe.
other end of the fiberglass pole assembly ..just peeping out of
the base and acting like an insulator at the base.
Right now..it is just held there in place with electrical tape. In
the next few days..I will be making a much more solid
arrangement than this.
FUTURE REFINEMENTS: 1) lubricate the threaded rod to
prevent corrosion. I am thinking of using a synthetic bicycle
chain open air grease.
2) Paint the 12 foot copper pole. Im thinking of basic black or
grey.
3) Try and order a Lexan clear plastic tube for the coil cover.
Right now..I am using a simple clear plastic map case. It is
sitting a wee bit crooked on the pipe.
| This article is still being added to ..from time to time..Originally wrote in October 2011; I add performance notes and perhaps modifications as they come about. NEW....(December 15th 2011) this antenna will operate 2 bands simultaneously! -- 40 meters and 17 meters particularly ..see the swr curves THIS PAGE (LINK) 73 Earl VE3AB (www.hamlectronicsmagazine.com) |
| The page I made about a week ago with pictures and swr curves for a manually adjustable version of this antenna is still available at this link here. |
I used electrical tape to tape the motor assembly and also to secure the motor to the
end of the fiberglass pole. Very "amateurish" and very "cheap and dirty" and one
could argue.. "UGLY CONSTRUCTION" ..but..it works. Electrical tape makes a good
strong joint. Surprisingly strong. I even used tape around the coupling joint where
the threaded rod joins up with the screwdriver bit and motor. (Just to make sure
nothing works its way loose). It works. My first qso was with NORM up in New Lisgard
Ontario who was controlling the Laurentian Net on 3755khz. He said I was around the
S-9 mark and about the same strength as a base station in Echo Bay near Sault Ste.
Marie On.
end of the fiberglass pole. Very "amateurish" and very "cheap and dirty" and one
could argue.. "UGLY CONSTRUCTION" ..but..it works. Electrical tape makes a good
strong joint. Surprisingly strong. I even used tape around the coupling joint where
the threaded rod joins up with the screwdriver bit and motor. (Just to make sure
nothing works its way loose). It works. My first qso was with NORM up in New Lisgard
Ontario who was controlling the Laurentian Net on 3755khz. He said I was around the
S-9 mark and about the same strength as a base station in Echo Bay near Sault Ste.
Marie On.
Here is the fingerstock assembly in the 2 inch pipe coupling. Here I slide it back and forth. I had too much tension on the coil so
I maniplulated the finger stock. I used two types of finger stock. One I bought on ebay from a California supplier. It was Laird
Speciality Instruments 97-515. Just search ebay for finger stock and you should find this. The suppier has a link to the
manufacturer web site as well.
I also had some silver plated finger stock that I had from a supplier on ebay from Slovakia republic somewhere. I used some of
that too in order to make a tight conductive joint.
I maniplulated the finger stock. I used two types of finger stock. One I bought on ebay from a California supplier. It was Laird
Speciality Instruments 97-515. Just search ebay for finger stock and you should find this. The suppier has a link to the
manufacturer web site as well.
I also had some silver plated finger stock that I had from a supplier on ebay from Slovakia republic somewhere. I used some of
that too in order to make a tight conductive joint.
NORMALLY, the fingerstock solders on the inide of the pipe. I soldered mine to the outside of the
pipe coupling. This was because my coil was too large a diameter for this standard method. I
re-enforced the structure and ..bottom line..it works. Here in Elliot Lake, we have no HOME DEPOT
STORES or large plumbing supply shops. Otherwise..I might have gone shopping for a copper pipe
coupler/adapter of a larger size diameter and would have soldered the fingerstock to the inside of the
pipe.
pipe coupling. This was because my coil was too large a diameter for this standard method. I
re-enforced the structure and ..bottom line..it works. Here in Elliot Lake, we have no HOME DEPOT
STORES or large plumbing supply shops. Otherwise..I might have gone shopping for a copper pipe
coupler/adapter of a larger size diameter and would have soldered the fingerstock to the inside of the
pipe.
I wrapped the coupling that joins the threaded rod to the motor with (WHAT
ELSE!!) ELECTRICAL TAPE! -- yES. i AM THE Red Green of ham radio. Red
Green is Canadian as I am Canadian as well.
Anyways.. the darn thing works and I can take care of the rough edges and
smooth out the wrinkles later.
If you look carefully at the copper tube you will se a bit of oxide/pitting
starting. I will be painting the tube shortly to protect it and keep it looking
nice.
ELSE!!) ELECTRICAL TAPE! -- yES. i AM THE Red Green of ham radio. Red
Green is Canadian as I am Canadian as well.
Anyways.. the darn thing works and I can take care of the rough edges and
smooth out the wrinkles later.
If you look carefully at the copper tube you will se a bit of oxide/pitting
starting. I will be painting the tube shortly to protect it and keep it looking
nice.
Previous to this copper pipe
version of the screwdriver
antenna, I made a similar one out
of aluminum.
The aluminum version was
manually adjustable. Non-
motorized. YOu clamped the joint
where the coil came out of the
aluminum support tube.
MFJ makes a type of manual
screwdriver antenna.
Anyways..the link below gives
information about this older
version I made up a week or so
previously.
NOTE: I will be keeping the old
manual version for Field use and
Field day and events like that.
version of the screwdriver
antenna, I made a similar one out
of aluminum.
The aluminum version was
manually adjustable. Non-
motorized. YOu clamped the joint
where the coil came out of the
aluminum support tube.
MFJ makes a type of manual
screwdriver antenna.
Anyways..the link below gives
information about this older
version I made up a week or so
previously.
NOTE: I will be keeping the old
manual version for Field use and
Field day and events like that.
Shown above: the fiberglass pole assembly (adjust by sliding the end pieces
farther apart or farther together). When the length is adjusted properly..this
whole assembly with motor and control wires slips into the end of the 12
foot copper pipe and the far end of the fiberglass tube just sticks out
enough to form a base insulator. To keep the fiberglass pole from spinning
when the motor is turned on..I used electrical tape to fasten the base
insulator end of fiberglass pole to the copper pipe. Very quick and very dirty
at this point...but it is working. Last night I was looking out the shack window
and watching the antenna coil go up and down.
farther apart or farther together). When the length is adjusted properly..this
whole assembly with motor and control wires slips into the end of the 12
foot copper pipe and the far end of the fiberglass tube just sticks out
enough to form a base insulator. To keep the fiberglass pole from spinning
when the motor is turned on..I used electrical tape to fasten the base
insulator end of fiberglass pole to the copper pipe. Very quick and very dirty
at this point...but it is working. Last night I was looking out the shack window
and watching the antenna coil go up and down.
| click here to go to PAGE TWO of this article which has more pictures and information about how I went about this project. |
Just like the old prototype ..the new
copper pipe version can operate two
bands with one setting of the coil.
ie when coil is on 7 mhz or 3.5 mhz
band ..(coil extended a fair
amount)..the antenna will be
resonant on 18mhz band with low
swr across the whole band.
copper pipe version can operate two
bands with one setting of the coil.
ie when coil is on 7 mhz or 3.5 mhz
band ..(coil extended a fair
amount)..the antenna will be
resonant on 18mhz band with low
swr across the whole band.
This first effort at a fingerstock collar did not turn out all that well. I did try to fix it up with
some other smaller fingerstock (silver)...but it ended up being too tight for the coil and I
decided to set this one aside and build another. If you go to later pages in this article you
will see the new fingerstock collar. It allows easy movement of the coil (up and down) AND
at the same time is snug enough to provide good contact with the coil windings.
some other smaller fingerstock (silver)...but it ended up being too tight for the coil and I
decided to set this one aside and build another. If you go to later pages in this article you
will see the new fingerstock collar. It allows easy movement of the coil (up and down) AND
at the same time is snug enough to provide good contact with the coil windings.
| page 2 of this article..follow the links in BLUE PRINT --------> |
| The first prototype of this antenna was made with aluminum tubing. It too was a 12 ft long 2 in. dia pipe/tube with a coil wound on a pvc pipe that had been machined with grooves for the coil windings. I did not use a fingerstock collar or fingerstock with this first version. I used sheet aluminum and I clamped the sheet aluminum to the coil at a predetermined point. I still have this early version and it could be used as a portable antenna for field day or |
| These antennas can operate 2 or more bands with one coil setting. |