I recently acquired a pair of Motorola T600 TalkAbout HTs, in hopes of using them to communicate with others while camping and hiking (etc.).
Unfortunately, on our first trip out we noticed two significant things: other HTs listening to either of my two T600s noticed a significant difference in audio output, as compared to other HTs; and the range of my two T600 was notably limited, when compared to others' FRS/GMRS HTs. When they turned up their (Rx) volume to where they could hear (Tx from) ours, they got a notable amount of distortion; making them almost unusable.
When I got home, I checked out my T600s against a Radio Service Monitor; and noted two surprising things, while they were transmitting on frequency, they were significantly under-deviating; and there was no detectable output difference between transmitting on High and Low power (even on a channel which allowed for higher power output). To confirm this, we did a local field test of the two (T600) radios; and noted that they could talk to each other; but their range was very short; and it didn't make any difference if we selected High or Low power (even on a channel that allowed High power).
Upon opening one of them, I noted that there are only TWO adjustable devices on the PCBAs (one near a crystal marked YC26.000, the other on the opposite side, near a shielded portion of the radio's electronics); and there was a white (presumably foreign contamination) substance on several portions of both sides of the PCBA. Beyond this substance, there were no other signs that the radios might have been exposed to abnormal conditions. In fact, other than this, the radios still appeared to be new.
I would guess that the adjustment near the crystal might adjust the primary oscillator, controlling input and output frequency; but I haven't fiddled with it to confirm this. I have no initial guess what the other might adjust (perhaps PL tone reference, but perhaps not).
QUESTIONS:
1) Are schematics available for these (T600) radios?
2) Is there any documentation describing radio alignment for the (T600) radios?
3) Does anyone know what the two adjustable devices do?
4) Is there a way to adjust the deviation?
5) Has anyone encountered a similar white substance deposit on the PCBA.
If these were the cheaper type of FRS/GMRS radios, I might be inclined to just toss them and buy another pair; but these cost a bit more then others (enough so that they might be worth at least trying to repair them), and I am concerned that the failure might be a more systemic indication of poor quality in the Motorola design or fabrication.
ANY technical input would be appreciated.
Unfortunately, on our first trip out we noticed two significant things: other HTs listening to either of my two T600s noticed a significant difference in audio output, as compared to other HTs; and the range of my two T600 was notably limited, when compared to others' FRS/GMRS HTs. When they turned up their (Rx) volume to where they could hear (Tx from) ours, they got a notable amount of distortion; making them almost unusable.
When I got home, I checked out my T600s against a Radio Service Monitor; and noted two surprising things, while they were transmitting on frequency, they were significantly under-deviating; and there was no detectable output difference between transmitting on High and Low power (even on a channel which allowed for higher power output). To confirm this, we did a local field test of the two (T600) radios; and noted that they could talk to each other; but their range was very short; and it didn't make any difference if we selected High or Low power (even on a channel that allowed High power).
Upon opening one of them, I noted that there are only TWO adjustable devices on the PCBAs (one near a crystal marked YC26.000, the other on the opposite side, near a shielded portion of the radio's electronics); and there was a white (presumably foreign contamination) substance on several portions of both sides of the PCBA. Beyond this substance, there were no other signs that the radios might have been exposed to abnormal conditions. In fact, other than this, the radios still appeared to be new.
I would guess that the adjustment near the crystal might adjust the primary oscillator, controlling input and output frequency; but I haven't fiddled with it to confirm this. I have no initial guess what the other might adjust (perhaps PL tone reference, but perhaps not).
QUESTIONS:
1) Are schematics available for these (T600) radios?
2) Is there any documentation describing radio alignment for the (T600) radios?
3) Does anyone know what the two adjustable devices do?
4) Is there a way to adjust the deviation?
5) Has anyone encountered a similar white substance deposit on the PCBA.
If these were the cheaper type of FRS/GMRS radios, I might be inclined to just toss them and buy another pair; but these cost a bit more then others (enough so that they might be worth at least trying to repair them), and I am concerned that the failure might be a more systemic indication of poor quality in the Motorola design or fabrication.
ANY technical input would be appreciated.
