Cobra 148GTL Technical Service Bulletin

6500 W. Cortland Street * Chicago, IL 60707 * Phone: 773-889-8870 * FAX: 773-622-2269
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June 3, 2003
TECHNICAL SERVICE BULLETIN
MODEL(S):
DESCRIPTION:
ACTION:
ADJUSTMENTS:
NOTES:
Consumer Response Group
148GTL, 148NWST
Squealing on transmit. Possible causes:
• High SWR
• Inadequate ground
• Microphone sensitivity of radio is too high. Specification:
− From 1 to 2mV for 50% modulation with Soundtracker off
− From 0.5 to 1mV for 50% modulation with Soundtracker on
One of the following suggestions should solve the problem:
1. Check the SWR of the antenna, make sure it is below 3.
2. Connect a ground wire to a screw on the side of the radio, to ground the
chassis of the radio.
3. Remove the top cover plate and tighten all the screws around the edge of the
circuit board.
4. If the radio still squeals, the microphone sensitivity of the radio is too high.
Change R126 to a 12K resistor.
If R126 was changed, check maximum modulation.
Page 2 contains a procedure for checking microphone sensitivity.
10020
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