DIR Return Create A Forum - Home
       ---------------------------------------------------------
       kycbradio
  HTML https://kycbradio.createaforum.com
       ---------------------------------------------------------
       *****************************************************
   DIR Return to: Midland Radio
       *****************************************************
       #Post#: 52--------------------------------------------------
       Midland 77-290 Channel Expansion
   DIR By: kycbradio
       Date: October 5, 2018, 11:08 am
       ---------------------------------------------------------
       Midland 77-290 Channel Expansion
       1. Remove top and bottom cover.
       2. Prepare an 8" small gauge jumper wire Tin both ends.
       3. Remove the 1K ohm chip resistor on the radio front panel
       4. At the removed resistor location, solder the  prepared jumper
       to the pcb pad nearest the center of the radio.
       5. Solder a 1K ohm 1/8 watt lead resistor to the other end of
       the jumper.
       6. Solder the free end of the resistor to the emitter  lead
       (lead nearest the rear of the radio) of Q61.
       7. Turn the radio over so the bottom of the pcb is facing up and
       the front is closest to you.
       8. Locate chip resistor R63 and remove
       240 Channels:
       Press and hold "DW" and "9" then turn radio on. Select bands by
       using the "19" button.
       To set for 28Mhz to 29.7 Mhz press and hold "LCR" and "eMIC"e
       then  turn radio on. To switch back to 40 channel mode repeat
       process.
       Microphone Gain:
       Chip resistor R138 controls mic gain decreasing the value of the
       resisitor increases the gain.
       Generally have a 270 ohm, the value can be as low as 150.
       If too much gain is used oscillation may occur.
       *****************************************************
       Page 1 of 1