All,

I am trying to measure impedance through a balun, or more accurately a 1:1 in
line "transformer". For test purposes the transformer is two windings of 10
turns each on a toroid. The winding are tightly wound on opposite sides. The
material is #43, the toroid is 3/4 inch OD.

If I drive one side of the transformer with one milliwatt at 4 MHz and terminate
the other side into 50 Ohms, and then measure the input voltage and the output
voltage. The output voltage significantly less then the input voltage, about 1/3.

The second measurement that does not support my understanding is: If I connect
the transformer up to an 8450A through appropriate couplers, and then short the
output the 8405A does not show a 180 degree phase shift between 'open' and
'shorted'. If this measurement is made without the transformer then the results
are as expected.

This is obviously something with the transformer. I would like to construct a
simple 1:1 in line transformer good from 3 to 30 MHz and 100 watts. What core
size, material, and windings are a good starting point for this?

Thanks - Dan - kb0qil