Post by midnight on Jan 30, 2011 15:12:24 GMT -5
Hi All,
I have three examples of the Johnson Messenger 250 base radio and have found that two of three of them have AC power supply problems (DOA). These radios have a DC input to power the radio as well and they do work when hooked up to a DC power supply.
That said, I am finding that when I plug them into AC power, there is 14.7 VDC detected at the on/off/volume switch, when in the OFF position. When I turn the switch on, the voltage disappears.
Anyone know what might be wrong in the AC power supply and how I might go about troubleshooting it? There is a simplified schematic on CB Tricks (Service Manual pp. 1-4) but I don't have much luck posting pics here.
I have not only the Johnson-branded Turner +3 mic that uses the 14V phantom power from the mic plug, but also the Turner CS-1 version of the +3 that uses its own 9V battery but is painted the same dull gold as the bezel on the Messenger. I get better reports on the Johnson-branded brown one (reports say the CS-1 is too bassy).
I hate to say it, but on the nicest example, which is clipped, I get better reports than I do on my Browning Golden Eagle 68 R/T. That's represented by a sum total of about $50 for the combo. It DKs about 2 watts on a Palomar 500 meter that's been calibrated to a Bird 43 on all three power output ranges.
Naturally, the receive isn't much on this radio and with three whole controls to operate, I don't feel too overwhelmed, LOL. But I'd like to see if it's cheap or easy to sort out the power supply issue and maybe learn something along the way. If not, I'll run them as is.
Forgive me if I don't respond with results right away. My work schedule is kind of unpredictable right now, so I never know when I'll get a chance to work on them. But if I know where to start, it'd sure be a great help. I'm very much a beginner with this stuff, so speak slowly, thanks.
I have three examples of the Johnson Messenger 250 base radio and have found that two of three of them have AC power supply problems (DOA). These radios have a DC input to power the radio as well and they do work when hooked up to a DC power supply.
That said, I am finding that when I plug them into AC power, there is 14.7 VDC detected at the on/off/volume switch, when in the OFF position. When I turn the switch on, the voltage disappears.
Anyone know what might be wrong in the AC power supply and how I might go about troubleshooting it? There is a simplified schematic on CB Tricks (Service Manual pp. 1-4) but I don't have much luck posting pics here.
I have not only the Johnson-branded Turner +3 mic that uses the 14V phantom power from the mic plug, but also the Turner CS-1 version of the +3 that uses its own 9V battery but is painted the same dull gold as the bezel on the Messenger. I get better reports on the Johnson-branded brown one (reports say the CS-1 is too bassy).
I hate to say it, but on the nicest example, which is clipped, I get better reports than I do on my Browning Golden Eagle 68 R/T. That's represented by a sum total of about $50 for the combo. It DKs about 2 watts on a Palomar 500 meter that's been calibrated to a Bird 43 on all three power output ranges.
Naturally, the receive isn't much on this radio and with three whole controls to operate, I don't feel too overwhelmed, LOL. But I'd like to see if it's cheap or easy to sort out the power supply issue and maybe learn something along the way. If not, I'll run them as is.
Forgive me if I don't respond with results right away. My work schedule is kind of unpredictable right now, so I never know when I'll get a chance to work on them. But if I know where to start, it'd sure be a great help. I'm very much a beginner with this stuff, so speak slowly, thanks.
