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         Radio Mods Database        

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KENWOOD TH-21A
Expanded RF 140 to 159 Mhz

1. Disconnect the battery and antenna.
2. Remove Knobs, antenna nut ring and plastic top
3. Remove front panel.
4. Locate switch unit (PCB X41-1590-00) This unit has the Vol.SQL etc.
5. Cut trace between R1 and R4 , R5
6. Install a jumper from the common point of R11 , R5 and 5C to the corner
of the tone switch.
7. Install a 1N914 diode and 48K resistor from the center top PIN of the
tone switch to the end of resistor R1. (R1 was cut in step 5).
Note: Cathode end of the diode goes to the tone switch top center pin.
Cathode end of diode has the line.
8. Adjust L10, L11, L12, L13, TC1, TC2, TC3 for maximum upper frequency
range.
9. Reassemble the radio.
10. Depress the tone switch to receive from 140 to 149 Mhz
Tone switch off for 150 t0 159 Mhz.

All mods found on this database are offered to me by other amateur radio hams or captured by Packet system. 
KB2LJJ  take no responsibility or liability for any damage done resulting from any modification.  
 I have been trying to help our ham radio with the radio modifications and have asked for any type of new radio mods.
 However, I haven't received too many.  If all of you contributed a little more,  I believe I would be able to help 
all the other ham's that are looking for these mods. I know it is possible to get more mods from all the Ham's because of
 the wide range that exist throughout the world.  By doing this we can  flourish and enjoy more of this hobby that 
we've taken part in for so many years. Furthermore, I ask you not to forget to send me any modifications that you might
 have through email.  I would really appreciate it.

      Email                webmaster@kb2ljj.com

 73's
   John Ribeiro
             KB2LJJ