hamelectronicsmagazine.com
NEW ARTICLE..July 23 2011 based
on brand new work on a dual band
vertical 17 mtrs and 6 meters for the
very top of my tower!!
on brand new work on a dual band
vertical 17 mtrs and 6 meters for the
very top of my tower!!
This is a short loaded vertical antenna that I made up for 18 mhz band. I mounted it on a mobile mounting bracket on the
side of my Ford Ranger for ease of adjustment and measurements. The Ford Ranger has a Fiberglass back cab but has
an aluminum strip grounded to the chasis for my antenna system. It is a light duty bracket for lighter antennas such as
the popular ham stick series.
This particular antenna is a bit of a hybrid! It uses the base section of a hamstick for 10 meters but on one end I screwed
on a hustler resonator. I could not read the writing on the hustler resonator because the lettering was rubbed off but I
(think) it is the 15 meter resonator.
Anyways..I adjusted the antenna so that the lowest swr was in the 17 meter band. Lowest SWR I could get was around 1.5
or 1.6 to one. So..I decided to make a base matching coil. I went to the ARRL handbook and it gave figures for a center
loaded 8 ft whip of about .3 microhenry.
I wound up a coil with nr 14 wire at around that figure and around 3 turns or so..it didnt work at all.
I figured more inductance would likely be needed. I then wound a coil with some aluminum wire of about nr 12 guage
and used 6 turns with an I.D. of about .8 inch and it seemed to be very good. SWR bottomed down to 1.1 to 1 and I then
adjusted the top whip for a resonance near 18.060.
NOTE: This antenna will not be used on my truck mobile. It will be going right to the top of my TV tower with the TGM mini
beam and little 2 meter beam. It will be mounted above these two small beams and will use the boom of the beam and
the 2mtr/440 yagi as a ground plane of sorts. I'm not sure this will provide a sufficient ground plane or not..but Im going
to try it.
With the loading coil the antenna has a nice swr curve in the 18 mhz amateur band. Snapshots of the swr analyzer being
used and the readings will show this.
Just for fun..I brought the swr analyser up to the 6 meter band. I kind of figured that the upper coil would isolate the
lower part of the antenna and provide resonance on 6 meters as well. IT DID SO ..VERY WELL. The six meter swr curve is
actually very good for the lower portion of 6 meters.
NOTE: The first 4 ft or so of the antenna is a type of hamstick for 10 meters. It is a wire meandering a bit under a black
PVC jacket. I think I used the antenna upside down in this case to have the male threads on the top of the section to
mate with the hustler coil.
SWR measurements below: after I used a matching coil at the base and I adjusted the adjustable section of the hustler
coil.
side of my Ford Ranger for ease of adjustment and measurements. The Ford Ranger has a Fiberglass back cab but has
an aluminum strip grounded to the chasis for my antenna system. It is a light duty bracket for lighter antennas such as
the popular ham stick series.
This particular antenna is a bit of a hybrid! It uses the base section of a hamstick for 10 meters but on one end I screwed
on a hustler resonator. I could not read the writing on the hustler resonator because the lettering was rubbed off but I
(think) it is the 15 meter resonator.
Anyways..I adjusted the antenna so that the lowest swr was in the 17 meter band. Lowest SWR I could get was around 1.5
or 1.6 to one. So..I decided to make a base matching coil. I went to the ARRL handbook and it gave figures for a center
loaded 8 ft whip of about .3 microhenry.
I wound up a coil with nr 14 wire at around that figure and around 3 turns or so..it didnt work at all.
I figured more inductance would likely be needed. I then wound a coil with some aluminum wire of about nr 12 guage
and used 6 turns with an I.D. of about .8 inch and it seemed to be very good. SWR bottomed down to 1.1 to 1 and I then
adjusted the top whip for a resonance near 18.060.
NOTE: This antenna will not be used on my truck mobile. It will be going right to the top of my TV tower with the TGM mini
beam and little 2 meter beam. It will be mounted above these two small beams and will use the boom of the beam and
the 2mtr/440 yagi as a ground plane of sorts. I'm not sure this will provide a sufficient ground plane or not..but Im going
to try it.
With the loading coil the antenna has a nice swr curve in the 18 mhz amateur band. Snapshots of the swr analyzer being
used and the readings will show this.
Just for fun..I brought the swr analyser up to the 6 meter band. I kind of figured that the upper coil would isolate the
lower part of the antenna and provide resonance on 6 meters as well. IT DID SO ..VERY WELL. The six meter swr curve is
actually very good for the lower portion of 6 meters.
NOTE: The first 4 ft or so of the antenna is a type of hamstick for 10 meters. It is a wire meandering a bit under a black
PVC jacket. I think I used the antenna upside down in this case to have the male threads on the top of the section to
mate with the hustler coil.
SWR measurements below: after I used a matching coil at the base and I adjusted the adjustable section of the hustler
coil.
I removed the coil and tried the measurements again and they were not good. The
base matching coil is pretty well necessary. Im not sure this one will be rugged
enough for up top of the tower where I wont have easy access to adjustments.
So I built another coil out of copper tubing. It didnt work at all. I suspect the
inductance was too low. What Iam going to do is measure the actual inductance of
this good coil and then wind a rugged outdoor coil of the same inductance and
use it up the tower with the antenna.
base matching coil is pretty well necessary. Im not sure this one will be rugged
enough for up top of the tower where I wont have easy access to adjustments.
So I built another coil out of copper tubing. It didnt work at all. I suspect the
inductance was too low. What Iam going to do is measure the actual inductance of
this good coil and then wind a rugged outdoor coil of the same inductance and
use it up the tower with the antenna.
This copper coil (wound using small diameter copper tubing I had around)
didnt work at all well. Swr readings were worse than if I used no matching
coil at all. The diameter of the conductor may add additional capacitance
between turns. It behaved much as the first 3 turn matching coil I had tried
previously. I would say: I would have to add at least 2 more turns to this big
copper coil..then it might work..(I think).
didnt work at all well. Swr readings were worse than if I used no matching
coil at all. The diameter of the conductor may add additional capacitance
between turns. It behaved much as the first 3 turn matching coil I had tried
previously. I would say: I would have to add at least 2 more turns to this big
copper coil..then it might work..(I think).
For fun..I tried a 15 meter super resonator coil on the top. This one has
a chunk of aluminum tubing stuck on top because I didnt have the
correct nut and whip length for the coil. IT DID RESONATE NICELY just
BELOW 21 MHZ and seemed to like my matching coil.
So the matching coil might work as well on 21 mhz just like it did ont 18
mhz.
On 50 mhz..the matching coil may not have all that much affect.
The 50 mhz band is a secondary consideration in my case. I might try
using it to hear 6 meter repeaters and spot openings on 6 meters. For 6
meters my primary antenna is the little TGM hybrid mini beam. On 6 it
works fairly well.
The large hustler (super coil) may not work the same when it comes to
allowing 6 meter operation.
NOTE: ALTERNATE MATERIALS: there is a fellow on the web who built a
antenna out of 1/2 inch copper tubing (commonly available). This
includes the threaded fittings which he made using copper end caps
and solder. His call is K0BG and I found his site quite easily with a
google search. You could homebrew this antenna using his ideas.
The advantage of my antenna (though) would be weight. My antenna
uses a fiberglass hamstick type 10 meter section. It is an important
consideration for my installation which will be on the top of my small TV
type tower. Mine is a (relatively) low profile city lot installation and I
have a good relationship with my neighbours. (This is necessary in a
small city like Elliot Lake (12,000 people) where everyone often bump
into each other quite often in public. By the way..Elliot Lake is very ham
friendly place. It is a former modern uranium mining center that has had
to reinvent itself as a retirement town and recreation center (mostly for
retired people). Climate is good and stable and infra structure is
modern too! Id say its a good place to settle down and do some
hamming activities like I do (and some outdoor stuff too!!)
a chunk of aluminum tubing stuck on top because I didnt have the
correct nut and whip length for the coil. IT DID RESONATE NICELY just
BELOW 21 MHZ and seemed to like my matching coil.
So the matching coil might work as well on 21 mhz just like it did ont 18
mhz.
On 50 mhz..the matching coil may not have all that much affect.
The 50 mhz band is a secondary consideration in my case. I might try
using it to hear 6 meter repeaters and spot openings on 6 meters. For 6
meters my primary antenna is the little TGM hybrid mini beam. On 6 it
works fairly well.
The large hustler (super coil) may not work the same when it comes to
allowing 6 meter operation.
NOTE: ALTERNATE MATERIALS: there is a fellow on the web who built a
antenna out of 1/2 inch copper tubing (commonly available). This
includes the threaded fittings which he made using copper end caps
and solder. His call is K0BG and I found his site quite easily with a
google search. You could homebrew this antenna using his ideas.
The advantage of my antenna (though) would be weight. My antenna
uses a fiberglass hamstick type 10 meter section. It is an important
consideration for my installation which will be on the top of my small TV
type tower. Mine is a (relatively) low profile city lot installation and I
have a good relationship with my neighbours. (This is necessary in a
small city like Elliot Lake (12,000 people) where everyone often bump
into each other quite often in public. By the way..Elliot Lake is very ham
friendly place. It is a former modern uranium mining center that has had
to reinvent itself as a retirement town and recreation center (mostly for
retired people). Climate is good and stable and infra structure is
modern too! Id say its a good place to settle down and do some
hamming activities like I do (and some outdoor stuff too!!)
On 6 meters...the bandwidth is really pretty wide. I would imagine if you built a
dipole for 17 meters using these components it would make a nice dual band
rota-table dipole. Other possibilities 10 and 6 (likely) 14 mhz and 50 mhz and
other combinations.
dipole for 17 meters using these components it would make a nice dual band
rota-table dipole. Other possibilities 10 and 6 (likely) 14 mhz and 50 mhz and
other combinations.
I wound this coil on a large socket wrench socket and it is somewhat
less than an inch diameter.
I will take it to my inductance measuring station and measure the
inductance and then wind a rugged outdoor version on a form and
weather proof it.
I will be writing PART 2 OF THIS ARTICLE IN A WEEK OR TWO WHEN I
GET UP THE TOWER AND MOUNT IT ABOVE MY LITTLE YAGI ANTENNAS.
I'm real curious to see if the SWR curves are about the same or if they
get skewed from being up in the air about 32 ft and without a large
ground plane.
Watch for part 2 ..in a week or two.
73 earl VE3ab
less than an inch diameter.
I will take it to my inductance measuring station and measure the
inductance and then wind a rugged outdoor version on a form and
weather proof it.
I will be writing PART 2 OF THIS ARTICLE IN A WEEK OR TWO WHEN I
GET UP THE TOWER AND MOUNT IT ABOVE MY LITTLE YAGI ANTENNAS.
I'm real curious to see if the SWR curves are about the same or if they
get skewed from being up in the air about 32 ft and without a large
ground plane.
Watch for part 2 ..in a week or two.
73 earl VE3ab
The very top of the tower is at about the 33 foot level..above the roof line and Im on a nice hill overlooking the surrounding terrain.
I will be mounting the 18mhz vertical whip right at the very top of the pipe. I will be strapping the vertical to a fiberglass tube inserted in the
support pipe. The boom and boom to mast plate and the cushcraft 2 meter/440 mhz yagi will (hopefully) provide enough aluminum up there
to act as a counterpoise. IF NOT..I may add a couple of 9 ft stainless steel cb whips strapped to the boom and running at right angles to the
driven element so as to act like two radials of close to 13 ft or so. That might work.
PART 2 WILL BE LOTS OF PICTURES AND RESULTS (HOPEFULLY POSITIVE) ..73 Earl VE3AB 23 July 2011..look for more articles especially
towards fall and winter when I really get back into more ham radio. Right now ..Im summer vacation and working outdoors and fishing too!
I will be mounting the 18mhz vertical whip right at the very top of the pipe. I will be strapping the vertical to a fiberglass tube inserted in the
support pipe. The boom and boom to mast plate and the cushcraft 2 meter/440 mhz yagi will (hopefully) provide enough aluminum up there
to act as a counterpoise. IF NOT..I may add a couple of 9 ft stainless steel cb whips strapped to the boom and running at right angles to the
driven element so as to act like two radials of close to 13 ft or so. That might work.
PART 2 WILL BE LOTS OF PICTURES AND RESULTS (HOPEFULLY POSITIVE) ..73 Earl VE3AB 23 July 2011..look for more articles especially
towards fall and winter when I really get back into more ham radio. Right now ..Im summer vacation and working outdoors and fishing too!
LINK BACK TO MAIN INDEX PAGE..
www.hamelectronicsmagazine.com by Earl Andrews VE3AB
(also I own www.earlandrews.com and www.sparetime.biz)
My email address is ve3ab@rac.ca -- and I welcome
correspondence.
www.hamelectronicsmagazine.com by Earl Andrews VE3AB
(also I own www.earlandrews.com and www.sparetime.biz)
My email address is ve3ab@rac.ca -- and I welcome
correspondence.
Without the matching coil on the base of this particular antenna, the
swr curves were not very good at all! (The SWR would not dip
below 1.5 to 1 anywhere in HF region. Now that I have tried this
with this particular antenna..I may try building a base matching coil
for my HF2V vertical.
This article will be worked on in the next week and polished up and
added to. I hope to add some swr graphs of the whip sans matching
coil and with the matching coil to better illustrate my point. 73 earl
ve3ab-- NOTE: one article on the matching coil that really stuck out
in my mind was the "dollar special" -- It was in either the ARRL
handbooks or ARRL Antenna Handbook back in the 1990s. This
fellow claimed the matching coil -- wound on a broomstick perhaps
if memory served me correctly..really improved his mobile antenna
setup. A roller inductor might be a good idea for multiband
operation with the bands marked in some manner.
swr curves were not very good at all! (The SWR would not dip
below 1.5 to 1 anywhere in HF region. Now that I have tried this
with this particular antenna..I may try building a base matching coil
for my HF2V vertical.
This article will be worked on in the next week and polished up and
added to. I hope to add some swr graphs of the whip sans matching
coil and with the matching coil to better illustrate my point. 73 earl
ve3ab-- NOTE: one article on the matching coil that really stuck out
in my mind was the "dollar special" -- It was in either the ARRL
handbooks or ARRL Antenna Handbook back in the 1990s. This
fellow claimed the matching coil -- wound on a broomstick perhaps
if memory served me correctly..really improved his mobile antenna
setup. A roller inductor might be a good idea for multiband
operation with the bands marked in some manner.
NOTE: I am a little afraid of lightning and also I want to keep a low profile..therefore..I selected the slim looking hamstick with the low
power hustler coil. It will not stand out too much and hopefully will give me decent performance up on top of the tower.
power hustler coil. It will not stand out too much and hopefully will give me decent performance up on top of the tower.
Below: the lower frequency where swr rises to 2 to 1 and the upper freq where swr 2 to 1
I will be tweaking and adding
some more to this article soon.
I plan to bench test the
inductance of the matching coil
and fabricate a rugged outdoor
version which will be stable in
the harsh northern conditions.
some more to this article soon.
I plan to bench test the
inductance of the matching coil
and fabricate a rugged outdoor
version which will be stable in
the harsh northern conditions.
LINK TO PAGE 2 of this article (dual band vertical 17m/6m)