All antennas once installed should have there VSWR (voltage standing wave ratio) checked. The factory pretuned antennas may be faulty, the connector may be faulty the location of the antennas may be affecting the antenna.
A vswr check will indicate of the antenna is ok, plus you can "tune" the antenna for best operation.
I have found the UNIDEN antennas to be very flimsy and they move around a lot while you are driving.
I would adviod using a 80 channel rig until all people are running 80 channels, as dependent on the receiver design of your 80 channel rig, the rig may block somee one transmitting on a old 25 Khz rig. The first 40 channels for both rigs are the same.
Im a radio tech