JC-4s manual version 9.1 page 4
The function of this special jumper is sometimes very useful. It will control the antenna output which is
NOT selected with the control box. There are 2 reasons for this jumper. To easy connect a ladder line
450 ohm wire and to prevent RF back into the tuner while using higher powers when used with single
wires or verticals. In some cases it is better to ground OR to not connect the not used output.
Example 1:
So if you select and tune antenna output A:
Connect the jumper in de right position and antenna output B will be floating. (not connected to
anything)
Example 2:
So if you select and tune antenna output A:
Connect the jumper to the left position and antenna output B will be grounded
