1270.3 THIS MOD WILL MAKE A SWITCHABLE NODE/MFJ FROM A 1270B OR A 1274 NOTE:TNC MUST BE UPGRADED TO 32K MEMORY FOR THIS MOD... PARTS REQUIRED : 1 27C512 EPROM 1 EXTRA 32 MEMORY CHIP FOR THE MFJ 1 1K RESISTOR 2 10K RESISTORS 1 DPDT MINI SWITCH HOOKUP WIRE. 1. MAKE ALL MODS ACCORDING TO THE NET DOCS TO MAKE A NODE OUT OF YOUR 1270B OR 1274 2. USING YOUR EPROM PROGAMMER, READ YOUR MFJ EPROM. BURN THE FIRST HALF OF THE 512 CHIP WITH THE MFJ DATA...BURN THE SECOND HALF OF THE EPROM WITH THE NET (2.06 OR 2.08 ARE BEST). CONSULT THE DOCS ON YOUR PROGRAMMER AS HOW TO DO THIS AS IT WILL VARY WITH THE TYPE OF PROGRAMMER. 3. FOLLOWING ALL SAFETY PRECAUTIONS FOR CMOS DEVICES CUT THE FOLLOWING TRACES. A:CUT TRACE FROM PIN 26 TO PIN 28 OF U24 B:CUT TRACE TO PIN 7 ON U12 C:CUT TRACE TO PIN 6 ON U12 D:CUT TRACE TO PIN1 U24 (IF ANY EXIST) 4. CONNECT PIN 1 U24 TO PIN 1 U25 5. CONNECT PIN 26 U24 TO PIN 26 U25 6. INSTALL PARTS PER FOLLOWING CIRCUIT DIAGRAM: U13 PIN 4 ------------- DPDT +5V 1K _____________ +5V 10K |------\ -------XXXX---===| PIN 1 | -------XXX--- \ | | | O O----------------- | 27C512 | U12 PIN 7 | | ---------------------O O-------\ | | \ | | U13 PIN 8 O O ----- | | ------------- / --- | | +5V 10K |------/ - | | -------XXX--- -------------- NOTE:PIN 1 ON THE 27C512 IS BENT OUT AND THE PARTS SOLDERED.. PLACE THE EXTRA 32K RAM CHIP IN SOCKET U24 TO SWITCH BETWEEN MODES POWER DOWN, FLIP SWITCH AND POWER UP..MEMORY IS DIVIDED 32K FOR EACH MODE.. WE HAVE 2 OPERATING NOW AND 2 MORE BEING CONVERTED.. THANKS TO TO THE FOLLOWING HAMS FOR THIS MOD.. WA6OTP JIM McNUTT WA6IKO JOHN OLSON WB7VMS JERRY KIME WB7VMS @ WB7VMS.#MURPHY.OR.USA.NA