Using an external current balun has a few advantages. By converting the ladder feedline to coax
away from the operating position, there is no unwanted feedline radiation in the shack. Reduced
noise and improved efficiency of the dipole will result and the structural proximity
considerations of ladder feedline can be greatly reduced or eliminated.
A high quality 4:1 current balun is ideal for this antenna and is available from DX Engineering
(part number
DXE-BAL200-H10-AT
). This balun provides better balance, often has lower loss,
and is more tolerant to load impedance and balance variations than most internal tuner baluns.
Use
Table 1
to ensure the ladder feedline is in
odd
multiples of 1/8-wavelength before
connecting to the balun. Use a good quality coax, such as Belden RG-213, from the balun to your
tuner.
Internal tuners may not have the operating range to tune this dipole on every band; therefore, use
of an external tuner may be needed.
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