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3 Stacked Yagi Antennas
The use of three antennas often represents a good compromise between increased antenna gain, mechanical feasibility, and satisfactory handleability
post 14 Aug 2024
Antenna for UHF VHF Links →
VHF/UHF Antennas - Using 75 Ohm TV coax instead of 50 Ohm Coax
Some use 75 Ohm coax exclusively and others never use it. Even though high grade 50 Ohm cable can be expensive, and 75 Ohm cable is readily available and cheap
YAGI 3 elements
Example for F = 145 MHz2.07m, spacings = 2.07x0.25 = 51.7 cm, reflector fed 151/F = 1.04m, elements alimentes 143/F= 98.6 cm 2 times 49.3cm, director = 137 / F 0.945mm, or a Boom of 1.05m, impedence = 50 ohms, gain = 7 DBD, RAV-AR = 20 DB
Yagi 9 elements 144mhz
The first director can be moved forward or backward to search for the best ROS
Yagi Uda 10 elementi 144mhz
Il boom e' lungo complessivamente 3 metri e 70 centimetri e puo essere realizzato in tubo di anticorodal o d'ottone
Yagi Ufh 18 element
Boom in aluminum of 2 / 2mm (tv) length 2.80 m,the parasitic elements may be isolated or not indifferently
155
Some use 75 Ohm coax exclusively and others never use it. Even though high grade 50 Ohm cable can be expensive, and 75 Ohm cable is readily available and cheap
Example for F = 145 MHz2.07m, spacings = 2.07x0.25 = 51.7 cm, reflector fed 151/F = 1.04m, elements alimentes 143/F= 98.6 cm 2 times 49.3cm, director = 137 / F 0.945mm, or a Boom of 1.05m, impedence = 50 ohms, gain = 7 DBD, RAV-AR = 20 DB
The first director can be moved forward or backward to search for the best ROS
Il boom e' lungo complessivamente 3 metri e 70 centimetri e puo essere realizzato in tubo di anticorodal o d'ottone
Boom in aluminum of 2 / 2mm (tv) length 2.80 m,the parasitic elements may be isolated or not indifferently
23cm Yagi Antenna building Finished antenna at 1275 MHz SWR under 1:1.5 at resonant frequency
50 MHz preamp Gain 26dB with the BFG135 Preamps for 144 and 430 MHz, for 50 MHz, the BFG135a is a cheap transistor and in my view rather strong. It is not easily damaged by static discharge or RF power. FG connection
30 Volt Computer Power Supply Stack A bonus was that i discovered that these did not need a standby load connected to the supply to keep them running just apply mains power and close the Start lead to ground