Fw: Re: [Antennas] Zo/Zl

[Sandy and Kees Talen]

OK based on all the input I've seen I draw the following conclusions
on driving a beam with ladder line:

My criteria:
1) 20/15/10m beam
2) 250 ft transmission line
3) lowest transmission line loss (using QRP to 100W max)
4) low cost 
5) minimum common mode curent on the balanced transmission
    line to minimize unwanted radiation on Tx and signal pickup on Rx.
6) Antenna tuner with balun available at the shack


OLD configuration....window ladder line all the way from the shack 
tuner to the beam.

Since the ladder line to the tower meets the criteria but the run 
up the tower is suspicious (even spaced out 12" from it) and the 
run around the rotor (inside heater hose) probably forces some 
unbalance (and is difficult to do) I've come to the following.

NEW configuration........

1) Homemade open ladder line from the shack to the tower with
   a "slow" twist for stability and water runoff. The usual no
   sharp turns, etc, etc.
2) A "Bill Orr type" coax 1:1 balun (16'- 8", 6-3/4" dia, tapped,
    and shorted as shown) at the beam to match it's balanced 
    load to coax.
3) Coax around the rotor and down the tower
4) Connect to the ladder line which goes directly out from the 
   tower using a 4:1 balun (much easier to make than a 9:1). 
   Does leave a mismatch but as I concluded earlier, not a 
   problem.

thanks,
73s  Kees K5BCQ


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