Outer Limits 4x4 Board

I purchased a GME TX3220 UHF Radio and have the problem that when you press the PTT button it changes channel. I some how figured out if I turn the radio on with the PTT depressed all is good but there surely must be another solution.
Has anyone got any ideas? (oh and the manuel doesn't mention it)
Jonesy

Well I have figured out I may have a microphone issue that some here may be able to help with. I tried a mike from another GME and all was good but they were different part numbers.
Can anyone with a GME TX3220 UHF please advise what part number is on the mike so I can see if I have the correct mike.
TIA
Jonesy

gday mate, i just looked through the packaging for my new uhf for this ahaha im still waiting to install mine, the number on the mike is mc 507 b i cant find an actual part number in the manual hope this helps
ryno

Gme sales manual from my store, mic part code MC507B $37.00 REC RETAIL

Have seen this type of thing before, the crystals in the screen sometimes flog out on that model too, it wasnt uncommon to intsall one and then require a new bloody face unit. GMEs problem, return with it to the store you bought it from they should replace the MIC straight away with one from stock and send your one off to GME.