| MY LITTLE MINI BEAM PAGES (TGM mini hybrid quad) 20,15,10,6 es 2 (yes 2 meters) - I used a coax choke balun to permit 2 meters. Swr is low. |
| THIS IS MY BASIC SET UP IN THE BACKYARD. THE TGM MINI BEAM DRIVEN ELEMENT IS ABOUT 8 FT OFF THE GROUND AND THE REFLECTOR IS ABOUT 6 FT OFF THE GROUND. IDEALLY..THE BEAM WOULD BE POINTING MORE TOWARDS THE SKY ABOVE..BUT ..THIS SETUP WILL PROBABLY GIVE REASONABLE RESULTS. I EXPECT THE RESONANT FREQUENCIES OF THE ANTENNA WILL SHIFT A BIT WHEN I put it up on the tower in a few weeks. Right now..I am playing around with it. |
This antenna is a four band antennna..BUT..it does have a couple of points of low SWR on 2 meters. One is around 144.2
mhz and the other is up around 144.7 mhz.
I have read where other amateurs found this to occur as well. I'm not paying too much attention to 2 meters. I have a
separate beam for 2 mtr ssb and fm.
On six the antenna is around 2 to 1 swr around 50.2 mhz.
mhz and the other is up around 144.7 mhz.
I have read where other amateurs found this to occur as well. I'm not paying too much attention to 2 meters. I have a
separate beam for 2 mtr ssb and fm.
On six the antenna is around 2 to 1 swr around 50.2 mhz.
NAVIGATION LINK BACK TO MY HOME PAGE
| Some photos of the original assembly and discussions follow: |
It was the night before Field Day 2006 when I first started putting this little antenna together. I had bought it second hand from a fellow in Alberta.
I spread out a blue tarp in the back yard and started assembly of all the little bits and pieces. The fellow who sold it to me had bagged the parts
and taped them together with labels. That really helped.
I spread out a blue tarp in the back yard and started assembly of all the little bits and pieces. The fellow who sold it to me had bagged the parts
and taped them together with labels. That really helped.
The reflector element is shaped like a quad element of
sorts. It has the same type of end loading coils with the
capacity hats as the Driven Element. Hence the name
Hybrid mini quad.
The Reflector element (seen in the background) is a little like a quad
element.
There is a cross arm assembly with a vertical insulator and a
horizontal insulator
(clear lexan tubing). The Reflector tubing pieces bolt together at a
diagonal near the loading coils. I'm holding in my hand some spare
pieces for the antenna (the tuning spokes). 4 to 6 of these spokes
are located on each of the four coils on each band 20,15 and 10. 14
spokes for each coil and 4 coils total.
The effect of removing 1/2 inch from one spoke for each coil results
in an increase in the resonant frequency of 250 khz for 10 meters,
150 khz for 15 meters and 100 khz for 20 meters.
sorts. It has the same type of end loading coils with the
capacity hats as the Driven Element. Hence the name
Hybrid mini quad.
The Reflector element (seen in the background) is a little like a quad
element.
There is a cross arm assembly with a vertical insulator and a
horizontal insulator
(clear lexan tubing). The Reflector tubing pieces bolt together at a
diagonal near the loading coils. I'm holding in my hand some spare
pieces for the antenna (the tuning spokes). 4 to 6 of these spokes
are located on each of the four coils on each band 20,15 and 10. 14
spokes for each coil and 4 coils total.
The effect of removing 1/2 inch from one spoke for each coil results
in an increase in the resonant frequency of 250 khz for 10 meters,
150 khz for 15 meters and 100 khz for 20 meters.
Opposite( pictured) is one of the tuning coils (without the
spokes). The coils seem to be potted in an RTV sealant of
some sort. I'm not sure if the factory did this or the previous
owner. (I suspect the previous owner wanted to keep the
coils weather proofed and he used RTV to coat and protect
them). The RTV is showing a few minor cracks..but I'm going
to leave everything the way it was sent to me and try it out. I
may consult TGM (the manufacturer), to see what they
recommend before I change anything.
Also pictured below is the Driven Element pieces. The
aluminum tubing slides over this grey PVC insultor.
Update: I spoke to the previous owner. These coils were
potted in silicone sealant from the manufacturer.
spokes). The coils seem to be potted in an RTV sealant of
some sort. I'm not sure if the factory did this or the previous
owner. (I suspect the previous owner wanted to keep the
coils weather proofed and he used RTV to coat and protect
them). The RTV is showing a few minor cracks..but I'm going
to leave everything the way it was sent to me and try it out. I
may consult TGM (the manufacturer), to see what they
recommend before I change anything.
Also pictured below is the Driven Element pieces. The
aluminum tubing slides over this grey PVC insultor.
Update: I spoke to the previous owner. These coils were
potted in silicone sealant from the manufacturer.
I recently corresponded with the owner of the TGM Mini
Beam company up here in Ontario Canada. He told me the
coils are coated with RTV. Note: If you ever use RTV make
sure it is a good quality RTV that will not corrode the surface
it is applied to.
The TGM fellow also sent me a couple of Manuals in pdf form
of the MQ1 4 band mini antenna. If you would like to look
over the manual..give me an email and I can send it to you
free of charge.
Beam company up here in Ontario Canada. He told me the
coils are coated with RTV. Note: If you ever use RTV make
sure it is a good quality RTV that will not corrode the surface
it is applied to.
The TGM fellow also sent me a couple of Manuals in pdf form
of the MQ1 4 band mini antenna. If you would like to look
over the manual..give me an email and I can send it to you
free of charge.
| Here are the MQ1 coils all on the picnic table. Some spokes are missing and others need to be cut to the correct length. The MQ1 uses end loading. This same method could be used on other frequencies. A scale version of the MQ1 dipole element could be made for 80 &40 Mtrs for example. There are 3 coils in series with a set of spokes for each coil. What I think happens in this multiband antenna is: on 10: the first coil provides the end loading and resonates the antenna. The other 2 coils act as a big choke to block or trap the energy. On 15 the first and second coil work together and the last big coil is enough inductance to act as a choke to block the energy. On 20..the whole coil assembly is used to provide end loading. |
| PAGE ONE -- ASSEMBLY TEST AND SOME EXPERIMENTATION |
Up in the air at last!! NOTICE the choke balun. I used RG8 for the main feedline then I spliced in an RG58 section in order to make a tight coil.
link to my next page concerning this little antenna
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This is my low profile tower and beam for the city. The inverted L is now not being used. I am going to try something different for the low bands. I'm
thinking of a low profile vertical antenna. I have a large shed with a tin roof to use as the ground plane. It will be an elevated ground plane..possibly a
system that resembles a very long hustler mobile antenna that I can easily access by tilting it over to change coils and play around with it. I will be
working on my low band antenna this spring (2008) and will make some photos and information available here on my web site as the project evolves.
thinking of a low profile vertical antenna. I have a large shed with a tin roof to use as the ground plane. It will be an elevated ground plane..possibly a
system that resembles a very long hustler mobile antenna that I can easily access by tilting it over to change coils and play around with it. I will be
working on my low band antenna this spring (2008) and will make some photos and information available here on my web site as the project evolves.
The antenna clears the roof top nicely and is easy to work on and does not look much different than a "big tv antenna".
SWR data for 6 meters...(to be completed soon)
Generally speaking..the swr on six is a little high over the entire band. High being around
2 or 2.5 to 1 (something like that).
For serious 6 meter work..a little tuner to tweak the swr might be a good idea.
Myself..I use a Ten Tec Transverter and I think it can take a bit of swr.
Generally speaking..the swr on six is a little high over the entire band. High being around
2 or 2.5 to 1 (something like that).
For serious 6 meter work..a little tuner to tweak the swr might be a good idea.
Myself..I use a Ten Tec Transverter and I think it can take a bit of swr.
SWR DATA FOR 2 METERS..(TO BE COMPLETED SOON)
Actually on 2 meters the swr is better than six meters in many spots. I dont plan to use this antenna
on 2 very often as I have a few separate 2 meter antennas.
Actually on 2 meters the swr is better than six meters in many spots. I dont plan to use this antenna
on 2 very often as I have a few separate 2 meter antennas.
SWR CURVES.
RED curve is the antenna up on the tower.
Black curves were done when the antenna was up off the
picnic table pointing skyward (somewhat).
When an antenna is adjusted near ground level..generally
the resonance point will go up in frequency as the antenna
goes up onto the tower. These curves pretty well followed
that trend.
Each coil has a spoke that is adjustable with adjustment
screws. You adjust the length of one spoke per coil to get
the resonance points correct for your frequency of interest.
RED curve is the antenna up on the tower.
Black curves were done when the antenna was up off the
picnic table pointing skyward (somewhat).
When an antenna is adjusted near ground level..generally
the resonance point will go up in frequency as the antenna
goes up onto the tower. These curves pretty well followed
that trend.
Each coil has a spoke that is adjustable with adjustment
screws. You adjust the length of one spoke per coil to get
the resonance points correct for your frequency of interest.