We struck an interesting compatibility problem recently between Tait TP9300 handhelds and Motorola radios.
The symptom was that the Tait user could not hear transmissions from Motorola radios, but could hear traffic from Hytera or CS-700s. The Hytera and CS-700 users could hear the Motorola traffic just fine. The Tait's RSSI display would show the channel as active but the TP9300 would never un-mute, and occasionally the Tait would think that the traffic was encrypted when it wasn't. Once in the 'channel is encrypted' state the Tait would then lock up and would no longer receive anything, including from the Hytera or CS-700 radios, until power cycled.
The problem was tracked down to the Motorola radios operating with the "TX interrupt" feature enabled. Something to do with the 'TX interrupt' protocol seems to confuse the Tait handhelds. De-selecting the 'TX interrupt' box in CPS on the Motorola radios cleared the problem, re-check the box and the problem comes back.
We've filed a bug report with Tait but I thought I would mention it here in case anyone else is having the problem.
Jeff
ZL2JG