Off center fed multiband antenna for 40 - 20 - 10m 4:1 300W SSB



Off center fed multiband antenna for 40 - 20 - 10 meter bands with frequency ranges of 7000kHz to 7200kHz, 14000kHz to 14350kHz, and 28000kHz to 29700kHz with overall length of 20.5 meters (~ 67 ft.) (arms length: 13.65m/ ~45ft., 6.8m/ ~22ft.), with 0dBd gain on 40m band. A maximum power load of 300W PEP SSB with the 4:1 ratio balun

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54,00 €

54,00 € per ks

Data sheet

Frequency range7000 Khz – 7200 Khz, 14000 Khz – 14350 Khz, 21000 Khz – 21450 Khz a 28000 Khz – 29700 Khz
Working band of the antennaApprox.130 kHz for SWR less than 2 (depends on the placement of the antenna in space)
Arms length13.65m/ ~45ft., 6.8m/ ~22ft.
Overall length20.5 meters (~ 67 ft.)
Gain0 dBd for the 40 meter band
Maximum power load300W PEP SSB
Antenna feed50 ohm coaxial cable
Mounting heightnot less than 6 meters (~20 feet) (the higher, the better)
Weight1,06 Kg

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The materials used to build this antenna have been selected with a focus on the best electrical and mechanical properties, and resistance against outside weather conditions. An equally important factor is the durability of these materials in the future.

For the dipole arms a hardened and prestressed copper line with a cross-section of 2,5sqmm and a harder PVC isolation is used.

On the box side of the dipole arm the wire is tipped with an eye for a M4 screw (made by ZES Dolny Kubin, Slovakia).

This wire is isolated with a shrink tube on both sides. The mechanical connection with the balun is made using a simple wire loop secured with a duplex wire clamp and, on the hanging rope side, a ceramic isolator(type 16C01 made by MFJ) is used, secured also with a duplex wire clamp.

The antenna balun with a ratio of 4:1 and a maximum power rating of 300W PEP SSB is made from a waterproof box of IP56 made by SCAME, model 686.205.

On both sides of the box are screws with closed hook ends; the screws are of size M5, and made using anticorrosion steel to ensure durability.

A more solidly made SO239 connector is used, with plastic diaelectricum, bolted to the box via anticorrosion steel bolts and nuts.

The balun transformer is wound on a ferite toroid core model AMR R1 with the respective measurments of (outer x inner x height) 36 x 23 x 15 mm.

The arms of the dipole are electronically connected to the transformer through a pair of M4 screws and nuts on both sides of the box.

The connector on the antenna serves only to electronically connect with the coaxial cable. For bearing the coaxial cable, use the attached rope (with inner core made by LANEX).