| Author |
Message |
    
Dick
New member
Username: Dick
Post Number: 2
Registered: 10-2003
| | Posted on Thursday, May 05, 2005 - 4:32 pm: | 
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Hi!
Any ideas on what gives with this unit.
The original final was 2sc2029 and was bad
A 2sc2078 was used as a replacement but the unit still won't transmit. It has base drive of 1volt p/p and 12.9vdc on the collector and the transistor checks good. It's a great old unit but
semms to be a pain right now. Thank You! |
2600
Advanced Member
Username: 2600
Post Number: 562
Registered: 7-2002
| | Posted on Saturday, May 07, 2005 - 12:51 pm: |
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Don't have any tech data on that model, but the final circuit should be generic enough.
Look for a quarter-Watt resistor attached to the base (left) leg of the final. When the final blows, it tends to short inside. The full 13.5-Volt power now feeds into a small resistor, usually between 10 and 30 ohms that goes to ground. If this part blows out, there is no DC circuit to ground for the base (input) leg of the fan. The final just won't deliver power with this circuit open, no matter how much RF feeds into it. In some radios, a tiny ferrite bead will be slipped over one lead wire of this resistor. Be sure to slide the bead onto one leg of the new resistor.
73
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Monk
Junior Member
Username: Monk
Post Number: 22
Registered: 2-2002
| | Posted on Saturday, May 07, 2005 - 4:01 pm: |
|
2600, The TRC427 is the same as a Cobra 25.
Monk |
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