-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
President madison issues
- Thread starter Staybolt
- Start date
I'd first clean the AM/USB/LSB 'mode' switch with some contact cleaner.
Then I'd check D33 and D34; can't remember ATM which one is used for USB.
This schematic is for a Realistic TRC-449; but it should be very close:
http://www.cbtricks.com/radios/realistic/trc_449/graphics/realistic_trc_449_sm_sch.pdf
Then I'd check D33 and D34; can't remember ATM which one is used for USB.
This schematic is for a Realistic TRC-449; but it should be very close:
http://www.cbtricks.com/radios/realistic/trc_449/graphics/realistic_trc_449_sm_sch.pdf
Also, make sure all of the crystals are properly seated and the sockets are in good condition. That can also cause the issue you're describing. It is also possible that one of the USB crystals may have gone fault. It can either be the the 11.2858 crystal, or the 7.8025 crystal.
~Cheers~
~Cheers~
Can't remember if the 7.8 MHz carrier crystals in that radio are in sockets, or soldered in place.
If they are in sockets, you can swap one for the other. If a bad USB carrier crystal is the culprit, this would make USB only appear to work, and AM/LSB would go dead.
Every other way I can think to check will call for one or another piece of test equipment.
73
If they are in sockets, you can swap one for the other. If a bad USB carrier crystal is the culprit, this would make USB only appear to work, and AM/LSB would go dead.
Every other way I can think to check will call for one or another piece of test equipment.
73