Julius Fazekas wrote:
> What distance from the tower is a good rule of thumb for the cage wires?
>
> Three is the minimum, would four be "better", as in easier to match, provide
> better isolation?
>
> Pondering this for a 48' mast for 80M, as I don't think I have enough on top
> to make it useful on 160...
>
>
A 48 foot pole on 160 without any top loading will result in low feed
point impedence and low efficiency even with a good silver plated
loading coil. It still may be better for DX than a low dipole. The cage
helps as well and 36" to 48" are fine...and 4 wires are slightly better
than three but not much. A 48' tower, appears short, but, with some top
loading like a tri-bander on top you will notice that such a radiator is
clearly better than a low dipole or inverted "L" in laying out a lower
angle DX signal on TX. Remember the tower need not resonate on 1.8. As
with many short 60 degree BC station tower installations, so much
depends on the ground system and the quality of ATU components. The
cage can only help making the match easier to achieve to a certian
degree. If you don't have a beam on top of your tower consider
constructing a 30 foot stinger out of graduating sections of aluminum
tubing or create some top loading by connecting in about 30 per cent of
your top guy wires if possible as long as the downward angle is not to
acute and is around 45 degree declivity or better.
73,
Herb Schoenbohm, KV4FZ
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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