uhf/vhf mixer for antenna input to tv

[electroking]

Just to make things clear, VHF is channels 2-13, UHF is 14-69.

The device you're looking for is not a mixer but a VHF/UHF combiner.
This will have an input for the VHF antenna, an input for the UHF antenna
and a common output for the 75-ohm connector on your TV. If you
get a device that has only a pair of screw terminals and one coaxial
connector, it is a simpte 300-to-75-ohm transformer and is not what
you need.

Assuming you have separate VHF and UHF antenna cables, you do connect
them to the combiner and everything should be fine. On the other hand,
if your antenna is truly VHF/UHF and has a single cable coming down,
it can be assumed that it has a built-in combiner, and you would simply
connect it to the input port of your TV.

Are you sure the antenna you have is designed for both VHF and UHF?