Batboard

Hello everybody for the first time.

I've got strange problem with Motorola GM1200 with 8 characters display. Transmiter is OK but from reciever there is a strange sound with modulation.
This isn't CTCSS. It sounds similar to brum but it isn't power line brum.
Frequency of this sound depends from the stranght of reciving signal (lower, when the signal is very good). I've checked power supply and antenna and all is ok.

More data - the radio also doesn't log into trunking network. I see that it sends propetly mpt1327 frame, network recieves it, and send proper response to radio, but radio does not log in. Personalization and network files are good.

It is definitely problem with radio.

I've got a question. Is it possible, that this mulfunction is a some kind of software problem or strange combinations with radio programming??

How can I solve this problem??

It is an hardware error(bad receiver).I had this problem an many Jedi radios.The best is to buy a new one on Ebay.

Andreas

Does the radio do this with the external speaker, internal spkr disabled?
Could be a microphonic VCO coil simmular to the problem in GP300, GP350, P110, and the GM series. The vibration from the internal speaker "rattles" the VCO coil causing modulation of the receiver injection.

I have seen this in Maxtrac/Radius mobiles too.

I will agree with Andreas. I have also seen Jedis with distorted audio, and most of the times the fault is located at the discriminator IC. Also, in some radios, audio is OK if the received signal is below some threshold and distorted if a strong signal is entering radio...
Jedis are very nice but quite fragile.
You'd better buy another and keep this for parts.

Paul sv2us