|AIR BALUN 1:1 2kW bez ferrytu|
|- 1:1 Air BALUN (NonFerrite) - |
- Technical data -
This balun is normaly used with broad-band antennas,- where gamma-match or other narrow-band matching is not sutable. I use this baluna whith logo-periodic yagi antennas.
Impedance ratio........... 1:1 Frequency range...... 3-30 MHz Power handeling........... 2KW- Making the balun -
Principle - The coils on an air balun is not different from an Ferrite-balun, in the layout above you see the principle. Two coils (Yellow & red) is used as straight thru-feed, one for center conductor an the other for the sheild conductor, they are connected directly to each dipole half, The blue coil is used for reversed 'pick-up' and balances the dipole connections.
The Air-balun is made on a plastic 'Nonconducting' core,- Use a pice of plastic tubing about 25mm in diameter and about 66mm long. Drill tree 2mm holes,- slightly in diagonal in one end, whith about 5mm distance. drill tree 2mm holes in the same manner in the other end of the tube,- distance between the two hole-rows is 49mm.
Hint! It is best to make one coil at the time, dont trye to put al tree on the core at once.