Eh? Log-periodic Yagis make great scanner antennas. You just have to flip them on their side.
That's it, TV is horizontal polarization and land mobile is vertical, so a
re-orientation would be in order. TV antennas are broadband, and give
a fair bit of gain where they're pointed (if that's what's needed). With
that limitation, I wouldn't make a TV antenna my only one; an omni-
directional is important, unless you are only listening to stuff from one
direction (rare).
Also, don't worry about a 75 ohm v. 50 ohm coax feed, it's not going to
have much effect. Only concern would be the type of coax and how much
loss.
Dave