Comar AV200 (Sirio GP 3-E) antenna

GP3E.jpg

The Sirio GP 3-E is a high-quality ground-plane antenna designed for land use. With its robust construction and efficient structure, it offers excellent performance and reliability for communication on shortwave frequencies. The GP 3-E is a popular choice due to its easy installation, compact design, and ability to effectively receive signals. The antenna can be easily adjusted for precise frequency tuning.

 

Technical Information

Frequency Range 135.0 - 175.0 MHz (by adjusting)
Type 360° Omnidirectional Antenne, vertical polarization, ground plane
Gain 3.65 dBi
Material Aluminum, copper, nylon
Impedance  50 Ohm
Connector SO259 (UHF female)
Length 1,48 m
Weight 570 g + (350 g Mounting)
Wind Loading 150 km/h
Mounting extra mounting (FT-3) for mast, handrail, and wall installation
Rail/Mast diameter 25 - 54 mm
Material Mounting Anodized Aluminium, Stainless steel

 

Installation

The assembly of the antenna is slightly more complex than with other antennas, but the coverage with the antenna is better when it is precisely adjusted. When you receive the antenna, you should find the following parts:

 

GP3E_Antenna_parts.jpg

Base (left) - All parts are screwed to the base, including the coaxial cable

Ground Plane Elements (3x top) - three identical tubes with threads at one end

Center Element (middle) - tube with threads and nameplate

Tuning Rod (bottom) - full aluminum rod

Accessories - screws, protection caps 

 

Start with the "Base" of the antenna and screw the "Center Element" onto it, making sure it cannot easily loosen. Now insert the "Tuning Rod" into the top of the "Center Element" and lightly secure it with the smallest set screw, ensuring that the "Tuning Rod" can still move.

Next, measure from the top of the "Base" to the end of the "Tuning Rod" (see image below), 1123 mm, and secure the "Tuning rod" with the set screw so that it cannot move anymore. Finally, double-check the length to ensure the frequency is properly set and adjust it if necessary. If everything is correct, you can place the small black protective cap on top of the "Tuning Rod".

 

GP3E_tuning.jpg
Antenna installation, fine-tuning length 1123 mm for AIS

 

Now, onto the bracket. Take the tube and attach the two brackets to it, ideally as far apart as possible. Make sure not to attach them to the tapered section, as this is where the antenna will be mounted later. To ensure proper alignment, you can lay the bracket on a table to tighten it. Again, make sure everything is fixed in place.

 

FT3_mounting.jpg
Ensure that the tapered section (left) of the tube faces upwards.

 

Next, you can decide whether to screw the bracket with the U-clamps onto a mast or railing or directly onto the wall. The wall installation will be challenging, and you should check if the ground plane elements are not disturbing. Screw the three "Ground Plane Elements" into the "Base" to see if everything fits and if nothing interferes at the end. However, it's advisable to remove the "Ground Plane Elements" again and screw them in at the end, as this makes further installation easier. You can still put the black protective caps on the "Ground Plane Elements" at this point.

Thread the coaxial cable through the tube and insert and screw it with the antenna. It is advisable to additionally use self-amalgamating tape here, though the connection with this bracket is already very well protected. Insert the antenna onto the top of the tube and secure it with the remaining two set screws. Again, make sure that everything is securely screwed in place and that nothing can come loose from the bracket.

If you haven't screwed in the "Ground Plane Elements" yet, now is the perfect time. Congratulations, the antenna is now assembled.

 

Links

How to install an AIS station > coming soon

Dipole antenna vs. directional antenna