Topband: High Z vs Low Z shunt feed tower
Mon, 6 Nov 2000 10:58:13 -0800

Ford, N0OQW wrote:

"That is what I have.  One 15kV 200pf door knob cap in series with the
Plus one other component -- the 9:1 un-un.

"It seems to me that as long as I can get the tower to take power
(resonate it) at the frequency of interest (1832), messing with the
shunt, etc., is just alot of work.  Rauch seems to feel that I'm
splitting hairs."
The tower does not have to be resonant to take all of the power you give
it.  When you adjust the shunt feed, you are not resonating the tower,
you are matching it to your feedline.

If you move the tap point down from the 450-ohm point to the 50-ohm
point, you'll be able to get rid of the un-un and the required gamma
capacity will be about 600 pF, three times what you're using now.  Tom
basically said to use the fewest number of components to reduce losses
and that the greatest amount of capacity is the most efficient.

73, de Earl, K6SE

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