A Shortened 7 mHz Dipole
The shortened dipole for 7 mHz was described by Ken GM4JMU in Sprat 74. It is
made from insulated wire - Ken used 24/0076. The coils are wound on 40mm ferrite
as above, with 40 turns of the same wire on 1.5 ins PVC tube and may be water
proofed if required. The balun at the centre is wound with miniature coax
(RG174U). Tuning is best done in the clear and the preferred method of adjusting
to resonance employed..
The same idea can be used to provide a mult-band doublet, by substituting
tuned feeder for the coax.
The dipole described would be useful for the amateur with limited space and
also for portable use.
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