Motorola MICOR High Band to 222 MHz Conversion
Modification Courtesy of SEITS
Original Concept and Images by David A. Cooley N5XMT

Step 1: Remove Aux. RX board from rear and Aux. control Board and set aside. They will not be reused.

Step 2: Remove Main Rx board and replace the following components with the values shown:

C108 - 27pf NPO disk
C113 - 2.2pf NPO disk
C109 - 39pf N150 disk
C116 - 2.2pf NPO disk

You need to remove the Metal shields from the 4 coils at the rear end of the RX board to access these Caps.

Remove the 2 screws holding item 29, then remove item 29. Unsolder 2 tabs on each of the item 12 shields

And remove.

Step 3: Connect Orange wire from Rx Board TP to location shown in Fig. 2.

Step 4: Modify Helical resonator coils per Figure 3. The resonators are held in with 2 screws each. Remove resonator assembly from main RX board before attempting to modify it.

If you are interested in purchasing altered coils for this modification,  Click Here

Step 5: Reinstall Main RX board.

Step 6: Connect Coax that used to go to AUX RX board antenna input to Main antenna input.

Step 7: Set channel jumpers on Control Board per figure 4.

Step 8: Tune per Motorola Manual.

NOTE: A GaAs FET Preamp may be needed for optimum sensitivity.

Page recreated by: Kevin K. Custer W3KKC
Copyright 1998 SEITS, N5XMT and W3KKC.

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