Topband: matching elevated vertical

[Steve Flood]

>W7LR wrote: Series 9.6 uH from resistive input, then 44 pf shunt across output.

>W5UN sent me to http://home.sandiego.edu/~ekim/e194rfs01/jwmatcher/matcher2.html
>which for a low-pass L setup gave me identical values to W7LR using the ON4UN package.

>N6IZ wrote:  If you have the room full length grounds can get you very close to 1:1  Of course you could also drop in a small inductance to tune out the -j115 complex load Z.


>N6WG wrote:  Assuming it isn't too much (power), you could wind a simple matching toroid transformer.
>You need a turns ratio of "sqr rt (75/50)" which is 1.22. This can be worked out as 10 turns to the 50 ohm side
>and 12 turns to the 75 ohm side.  Then any minor swrremaining can be adjusted out at the rig.


Thanks for the tips everyone.  I decided to fly the balloon and measure the impedance.  52 - j92.   Not too far off from the modelled value.
I went ahead and added some more wire to the ends of my radials to get to 132 feet.  Tough to do through the trees and branches and trespassing onto the neighbors across a road, but I ended up with 53 + j21.  I shortened the vertical radiator a little at a time and got down to 52 +j10.  Pretty good, but had to quit experimenting when the balloon popped.  I think I'll build up the L-network and 1.5:1 balun ideas and try those too since I can't leave the full length radials up.  Perhaps I'll try to bend the radials to avoid private property.

Steve KK7UV