MEF-107-2K-Plus Multi-Band End Fed Half Wave Antenna Transformer 75:1 Ratio. Installation plate with U-bolts for Pole or tower leg installation up to 1.75 inches in diameter is included, along with two stainless steel wire clamps and one end insulator. Now you can make your dream low band antenna with just 259 feet of wire (79m) and operate on low bands without the use of tuner at legal power using as much as 2kW ICAS. Features massive ferrite core weighing 1.25 pounds (0.54kg) and very low Insertion loss. This is an End-Fed Half-Wave antenna (EFHW) transformer covering 160/80/60/40m amateur bands or any frequency in between.
It transforms high impedance 3750 Ohms at the end of the half-wave radiator to 50 Ohms and features very low insertion loss. Average insertion loss from 1.8-7.3MHz is less than 0.25dB. NOTE: for decent efficiency and match the minimum height for a horizontal portion of the antenna is 0.1 wavelength above ground (50 feet or 15 meters for 160M band). It will work fine on 30feet (9 Meters) too but the impact on tuning (SWR) and efficiency might be compromised.Just adding a wire radiator of 259 feet makes this antenna resonant on 160/80/60/40m. The wire of 133 feet will give you low VSWR on 80 and 40m.
Just add 1/2 half-wave wire to this transformer and tune the length to your preference. Note that the antenna will be working on multiple frequencies. Half-wave for 160m (259 feet) will be two half-waves on 80m and four (4) half-wave on the 40m band. If you desire to use it on any frequency between 1-8Mhz Like for MARS communications just cut the half-wavelength wire for that frequency or any frequency from 1-8MHz.
The wire length can be calculated by the following formulas. Length (feet)= 468/Frequency (MHz) or. Length (meters)=142.5/Frequency (MHz). Always cut a wire a bit longer to allow for tuning to your desired frequency.
Tuning depends on height above ground and nearby objects. There are so many ways to install the wire and your imagination is only limit. You can do it horizontal, vertical, sloping, an inverted? Such an antenna will not need radials and in most cases NO Tuner at all.Be a HAM and do some experiment. Grounding at the lug next to the SO239 connector is recommended! Long wires tend to collect electrostatic charges (usually when the weather is stormy) which can produce ESD (electrostatic discharge) at the end of your cable and damage your equipment. No guarantee or liability is either expressed or implied pertaining to damages to persons, buildings, or equipment in the installation or use of our antennas. You must use extreme caution when working around power lines. If the antenna were to come into contact with a voltage carrying line it could be fatal. The item "EFHW Transformer 751 (375050 Ohms) MEF-107-2K+ 2kW ICAS 160-40m" is in sale since Wednesday, September 2, 2020. This item is in the category "Consumer Electronics\Radio Communication\Antennas\Ham, Amateur Radio Antennas". The seller is "myantennas" and is located in Tampa, Florida. This item can be shipped worldwide.