John, you don't necessarily need a balun. Not knowing your installation, I
would most likely split the coax at the feedpoint (which, for longwires, can
be virtually anywhere), and run the shield to ground (counterpoise, etc.).
No balun needed...

- Mike KI6PR
El Rancho R.F., CA

"P N P" wrote
Could someone direct me to a site that would show me how to build a balun
for my long wire antenna to allow me the use of 50 ohm cable down to the
receiver ?
T.I.A.
John