| Author |
Message |
    
Bulldog369
Intermediate Member
Username: Bulldog369
Post Number: 253
Registered: 2-2004
| | Posted on Tuesday, March 29, 2005 - 8:06 am: | 
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ACCUIRED A 142 THAT THIS RADIO RX'S VERY WELL BUT WHEN YOU KEY THE MIC IT CUTS THE RX OUT BUT IT IS NOT SWITCHING THE RADIO INTO TX MODE.. ANY IDEAS.. |
Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 337
Registered: 9-2004
| | Posted on Tuesday, March 29, 2005 - 11:20 pm: |
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hey bulldog, what does the S/RF meter do when you key the mic?
does it fall to zero like you were on SSB and not talking? or does it still move with received signals with no speaker audio?
if the meter falls to zero, then check the driver and the final, then check the volatge regulator. (MB3756) i would just buy replacements as they're pretty cheap. (try RF Parts Co.)
if, however, the meter still moves around like you were receiving; then the problem is probably inside the microphone, ie. a broken wire, or dirty switch contacts. if this is your problem, unless the mic is really expensive, just replace it. its just as cheap as trying to fix one.
hope i helped
matt |
2600
Advanced Member
Username: 2600
Post Number: 530
Registered: 7-2002
| | Posted on Wednesday, March 30, 2005 - 5:07 pm: |
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Hey Bulldog,
The very first two tests we use on a radio with this problem are performed without removing the case.
1) Does the transmit/receive light on the front panel change from green to red when you key the mike? (You didn't say) If not, another known-working mike is the next thing to try. If it still flunks this test with a known-good mike, it's screwdriver-and-scope time. When the transmit light won't turn red, this points to trouble in low-power switching circuits and NOT to the power stages, like the final or AM modulator.
2) If it passes test #1, put it on (either) SSB mode, turn the mike gain to max and see if the transmitter shows power with SSB modulation.
These two quick tests can narrow down the troubleshooting a great deal even before you pick up a screwdriver.
73
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Kid_vicious
Intermediate Member
Username: Kid_vicious
Post Number: 341
Registered: 9-2004
| | Posted on Wednesday, March 30, 2005 - 6:21 pm: |
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thanks 2600, im learning more and more from your input.
matt |
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