RADIO AMATEUR SERVICE (WHAT IT IS?):
Α radio communication service that has as aim the self- teaching, the communication with each other, the technological research, and the telecommunications support of enterprises of help in cases of situations of an emergency and of destructions that are carried out by amateur, that is to say by persons permitted to deal with the radioelectric technique exclusively for personal aim and without economic profit.
YAGI 3 ELEMENTS 7db Gamma Match Portable
FREQUENCY : 144 -146 MHZ - GAIN: 7DB Front to back ratio 35 db. - VSWR :< 1.1 - MAX POWER RATING : 500 WATTS
IMPEDANCE :50 OHMS - MAX WIND VELOCITY:120 Km/h
Construction of antenna Yagi 3 Elements with Gamma Match, Portable.
The construction of the antenna is quite easy. I used the materials i had
in storage from older constructions.
To sum up, so far we have:
REFLECTOR = 1017 mm
Now we are going to find the distances between them.
we are going to use a stable capacitor 12 pf for gamma match. In this way we save weight since the antenna is mending for portable use. We connect one of the ends of the capacitor in the central pole of the connector and the other in small screw of gamma match. Do not try to stick to aluminum, the soldering is not going to be affective. We pierce a point of the gamma match and we a little screw at the top as you see in the picture.
In total the length of gamma match is 350 mm.
There's still the jumper which is a rectangular piece of aluminum with dimensions 11
x 56 x 18, H x W x B with two little screws sideways to keep the elements
distance between the active element and gamma match is 2 cm.
We Pierce at first for the connector, the side of the 3x3 box ,and 3cm at the bottom we adjust the Teflon in order to fit perfectly. After the hole in the Teflon for the tube of the gamma match and we are ready. Take a look at the Photos. They gonna help you a lot.
YAGI 3 ELEMENTS 7db Gamma Match
All the antennas that I construct, I want them to be strong and long-lasting.
Of course i want it to be light weighted, when it's portable. The construction is simple. Searching on Google I found this plan. In explicit detail, I would say it's easy, without any hard-to-find materials. Thought I've made a few modifications. When I started the construction, I used materials that I had already stored .But now let's move on the construction of the antenna.
1 Copper tube cu Φ15
1 Equal Tee cu cu Φ 15
1 90░Elbow cu Φ15
1 piece of Teflon 95X30 mm (drawing C)
1 Racor for Φ15 for portable use only
1 SO 239 connector
For the construction of the antenna, it's necessary some experience, regarding the soldering, but there aren't any technical difficulties.
We will also need some tools like:
A hacksaw or a pipe cutter
Propane device, soldering, soldering paste
(You will find them in stores that sell plumbing equipment)
Calculate the dimensions of the pieces. Start out by cutting them according to the dimensions, that you want the project to have. Always remember that for any type of construction, it's wise to measure twice and cut once! After cutting them, use the sandpaper in the places that are going to be soldered. This kind of work should be done in a workbench, so as the pieces are aligned. If you follow the dimensions of the project, you will have a static 1:1 SWR.
Begin by soldering the pieces as it's shown in the pictures. Apply the soldering paste in the place to be soldered and heat the tube with circular motions with the blowtorch (mapp gas). When the tube is heated and the soldering paste has melted and foamed, we use the soldering. That's all. Be careful not to burn yourself!
With the use of devices such as mapp gas it's needed that we take all precautionary measures and follow the instructions.
We solder all the pieces and now we solder the connector, heating it as little as possible in order not to destroy the insulator Teflon or Bakelite It's better if we have tied a little wire at one side of the connector, in order to solder properly. After the process, we cut it. Join the connector's positive edge with the single wire 2.5 and go to the opposite tube. Then spin it and solder it as well.
About the version J POLE PORTABLE, it's needed to be cut to the point that the design is showing and then solder the Racor. I prefer the Racor because it screws and unscrews many times without a problem. In order to make the J POLE PORTABLE more strong, put the Teflon piece as it is shown in the drawing C before you solder the Racor. In the end, the antenna was cleaned. I used the sandpaper in all of it's length and a special paint for non-ferrous metals.
I've taken this antenna in several mountains. The reason is that it is easy to assemble and has a good reception. Of course, if it is compared to the Yagi Gamma Match 3 Elements that I have made, it is quite below, according to the reports, that I've taken. It's advantage is its circular polarization. From SHACK and especially from Tripolis it opens several transponders like RO Laconia, RI Athens, R2 Dolianon and R7 Penteli. So, it competes the commercial antennas.
The tests are about to continue so as to make some final conclusions. For this construction I would like to thank my friend Kostas c190 for his valuable help. Take a look at the Photos.
YAGI 5 ELEMENTS ULTRA LIGHT PORTABLE 8.2 db
The designs of the antenna are from DK7ZB's site.
The antenna gain is 8.2 db.
It consists of
For further details look at the
ELEMENTS 144 MHz 8.2 DB PORTABLE
The designs of the antenna are from DK7ZB's site. www.qsl.net/dk7zb/start1.htm
The antenna gain is 8.2 db.
It consists of
For further details look at the pictures.
YAGI 5 ELEMENTS 144 MHz 8.2 DB PORTABLE
GREECE - HELLAS
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Tripolis. All rights reserved.
Last Update: 04 / 01 / 2018.