Interesting comments. If current antenna will tune 6M thru 20M then
conductive element length varies from minimum of 10ft (on 6M) to 36ft (on
20M). That means that each half of the element is able to change length
13ft. (36-10/2=13)
Apply this to a 30/40M antenna full size assuming 50ft (30M) and 66 ft (40M)
element length yields 8 ft (66-50/2=8) of adjustable length per side as is
currently used. The spool could even be smaller in size (less amount of
adjustment). Instead of a minimum of 5ft per side (6M) a 30/40 would have
about 25 ft per side minimum length for the highest frequency.
This would require a longer conductor and fiberglass element. Added
friction might mean a larger drive motor.
I have just used approximate lengths above for the concept (length of
reflector in most cases). Just the mechanical aspects of such an antenna
seem to be the major problem.
Lets see: 3el on 40ft boom at 120ft should play nicely on 30/40M.
73 de Arne N7KA
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