Multi-band symmetric dipole
On the radio RB4IX to work in the range of 1.9...14 MHz is used dipole with length on the shoulders of 41.5 m powered with a symmetric line R-300 Ohms. However, with the direct connection of the supply line to the transceiver transforming properties of the P-loop is not enough.
To enable adjustment of the P-loop between the supply line and TRX uses a simple matching device consisting of a variometer and SHPT 1:4 (Fig. 1). Coil diameter 50 mm contains 63 round wire with a diameter of 1 mm.
Approximate number of turns range: 1,9 MHz - 63; 3.5 MHz to 30; 7 MHz - 20; 14mgts-5.
The setup consists in choosing the number of turns of the coil for maximum illumination of all four neon lamps. The electrical circuit SHPT shown in Fig.2.
SHPT is wound in three wires 10 turns (stranded, tinned) on the package of the five rings 2000 NM with a diameter of 50-60 mm. wiring diagram SHPT shown in Fig.3.
Comparative tests showed that the LF bands, this antenna is almost as good as full-sized triangle on 80 meters TVI brand is missing on all ranges when RA on three GO with grounded grids.
Author: V. Najdowski, (RB4IX), Donetsk; Publication: N. Bolshakov, rf.atnn.ru