Скачать с ютуб Convert 148 to MOSFET в хорошем качестве

Convert 148 to MOSFET

CONVERT THE COBRA 148GTL TO MOSFET FINALS. NOTICE; USE AT YOUR OWN RISK. AUTHOR IS NOT RESPONSIBLE FOR USE. 1. Remove TR38, TR37 and TR36. 2. Replace VR8 and VR9 with 100K ohm variable resistors. Note; If there is a 47uf electrolytic capacitor next to VR9, remove it. 3. Remove R209, C200 and C226. 4. Remove C151, C149 and L40. 5. Remove D49 and D50 MV1Y diodes. 6. Replace C152 with a 1,000 to 1,500 pico-farad capacitor. 7. Replace R181 with a wire jumper. 8. Replace R179 (Next to VR8) with a 27K to 30K ohm 1/4 watt resistor.**(Thank you Jonathan1806) 9. Replace L43 with a 330K ohm 1/4 watt resistor. 10. Install IRF520, FQP13N10, ERF2030 or similar MOSFET transistors in TR38 and TR36's positions. 11. Install EN396DR from Gate + (Pin 1) to Source (Pin 3) of TR38. (Use C226 holes) 12. Install EN396FN from Gate + (Pin 1) to Source (Pin 3) of TR36. 13. Connect the center of VR8 to the Gate of TR36. *(The 330K ohm resistor that replaced L43 connects VR9 to the Gate of TR38.) 14. Replace R183 (predriver circuit) with a 5.6 ohm 1/4 watt resistor. 15. Connect a 100 ohm resistor from pin 10 of IC5 (XMT Mixer IC) to ground. 16. Replace L39 and L42 with heavier inductors, I use J.W. Miller P/N:5230-RC or 5220-RC Mouser part # 542-5230-RC or 542-5220-RC ** To set the bias; Disconnect the 12 volt supply jumpers (Violet and Green) to remove power from the Drain of the new finals. Switch to SSB. While measuring the voltage on the Gate (pin 1) of TR38, adjust VR9 for 3.5 to 3.6 volts. While measuring the voltage on the Gate (pin 1) of TR36, adjust VR8 for 3.2 to 3.3 volts. Reconnect the 12 volt final supply jumpers. Installer notes; If the radio will not transmit in SSB, measure the voltage on pin 8 of IC 4. If it drops below 8 volts the radio will not transmit. If this is the case then you have the final bias adjusted too high. Back it off until the radio transmits every time the mic is keyed. **Updates