At 02:51 AM 11/28/2007, Ryszard Tymkiewicz wrote:
> > Actually the tower is 52' with a force 12 c3 trapless tribander at the
> top and another 10' of mast with a dual polarity 10 element
> > 2 meter beam on top of that. What effect does the hf or vhf beam have
> on the action of the feed? also the tower is guyed at 45'
> > and the guys are insulated from the tower. There is also a house
> bracket at 18' and it is electrically connected to a metal gable
> > vent and there is a cross arm at 30' with a fm broadcast yagi and a
> scanner ground plane on it The tower has 3 ground rods 1 by
> > each leg with 30' of buried copper wire clamped to each leg and running
> 3 directions, 1 direction terminated with another ground
> > rod and connected to the shack ground. there is a alpha delta twin
> sloper mounted just 2' below the hf beam and it uses the tower
> > as a counterpoise also. At 47' there is a uhf atv yagi attached to 1 leg.
> > With all this baggage do you still think feeding the tower is a good
> idea? I see far too many rf paths to decouple.
>
>Jim I had similar doubts before I decided to my tower as a shunt feed.
>I have only one tower and all antennas for 10 bands are on it. I have X7
>with 2 elements for 30m above it 7 elements
>for 50 MHz on 8 meters boom. On the level of 18m I have 2 elements wire
>delta loop for 40m and 2 half slopers
>for 80m. As you see many antennas and wires ...and the shunt feed tower is
>working very well...for 3 years I worked
>10 new ones (to #290). So ,the best idea is just to try it...
>
> 73 GL
> Rys
> SP5EWY
I second this motion. My 31-meter tower has a 40m yagi on top and two
tribanders at 31 and 21 meters, but the real kicker is that I have a 4 x
80m lazy-vee dipole array, fed through coax that foes up inside the tower
to the 10-meter level and then out to the dipoles. When I set about shunt
feeding the tower, I could not find a tap at 50 ohms anywhere on it,
despite the help of K6SE and others. I then went to an omega match, which
proved absurdly easy to tune for minimum SWR.
At times I have had as many as 12 radials down, but think that currently
probably only 5 are intact. Still, it transmits a lot better than I
receive - with only 200 watts output, I have broken a lot of CW pileups on
topband. I'd say give it a go - nothing to lose.
73, Pete N4ZR
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