|Cherokee AH-50 HT Mods [message #52]
||Fri, 28 April 2006 22:58
Registered: December 2004
Here is an output power mod for the popular Cherokee AH-50 6 meter handie talkie. It is the first mod I've ever seen for this radio. Regular high output is just under 5 watts. After this mod you can get about 6-7 watts output while using an external 12 volt dc input and on low power about 3 watts is typical.
1.Remove all external screws and carefully pull apart the unit. Be careful not to lose the rubber PTT and feature button pads that will become lose while doing this as well as the plastic slider that locks the battery pack and power cord in place.
2.You will notice there are two separate,sandwiched circuit boards that make up the unit, one is the CPU and LCD display, the other is the RF component section. Gently pull the display board free of the RF section. They are joined together by a multi-pin terminal.
3. With the RF section fully exposed you should see a metal grounding pad that covers the underside of the RF section as well as the rf output coaxial wire. Desolder the legs of the grounding pad, as well as the lead of the coaxial wire closest to the BNC and move the grounding pad to the side, exposing the underside of the board. Use extreme caution as there are multiple surface mount components very close to these points.
4.Find the main output transistor-2SC2078 marked "C2078". It very easy to spot. It is screwed onto the radio's heatsink. With the grounding pad moved, you can now desolder the three pins on this transistor and remove. Replace with a 2SC2166. Be sure to use heatsink compound on the back of the new transistor and the heatsink during replacement. Locate an inductor with a core behind and to the left of the output transistor. There is a small hole in the heatsink above it for tuning. Tune this and all the other spring-like coils around the output final for maximum output at 53 MHZ. Make sure the radio is set on high power for this! You should see close to 6-7 watts output now, instead of the stock 4.8 watts. Rebassemble radio in reverse order and enjoy. Don't forget the radio will put a big strain on your battery pack on high power with the higher output. It is advisable to use low power setting with battery use and high only when an external 12v source is applied.