Modifications for the Kenwood TM-701

TM-701A repeater cross-band modification


Perform the following modifications to allow the TM-701A to operate in the repeater cross-band mode.
MODIFICATION:

  1. Disconnect the power supply and antenna.
  2. Remove the top and bottom covers (12 screws). Disconnect the speaker wire from the transceiver.
  3. Locate the green jumper wire show in figure 1. Using a sharp pair of wire cutters, cut the jumper in half.(green jumper)
                                    ______
                     ______________ |    |_____
                     |        TOP             <|---- Green Jumper
                     |                         |
                     |                         |
                     |    Heat sink            |
                     |             |           |
                                   |
                                   /
                               figure 1
    
    CAUTION:
    Cutting the green jumper allows the TM-701A to transmit from 142 to 151.995 MHZ. Protect your license by only using frequencies that you are authorized to transmit on.
  4. Solder a jumper wire to the foil side of the TX-RX board as shown in figure 2.
                 ______        ^
               __|    |________|________________
               |         Display side          |
               |             X ......          |          X = Screw
               |             X ......          |
               |                    - ----|    |
               |         ..............   | <----------  ADD Jumper
                             .            |
                   Pin #3    :____________|
                             :
                               figure 2
    
  5. Assemble the transceiver by reversing steps 1 -2.
  6. Reset the microprocessor by holding in the MR key as the power is turned on.
The repeater cross-band operation allows the TM-701a to receive on one band and re-transmit the signal on the other band. The TM-701a alternately displays the two bands until a signal is received. The transceiver will then display the band that is re-transmitting the signal. The SHIFT function cannot be used during the repeater cross- band operation. If the TONE or CTCSS function is required, only one ETA tone can be used for the two bands.

OPERATING PROCEDURE

  1. Select the operating frequencies for both bands.
  2. Set the squelch control to the threshold point. The TM-701a will transmit in the repeater cross-band mode if the squelch control is set too low or a signal is received.
  3. Place the transceiver in the duplex mode (F + DUP).
  4. Press the F key for longer than one second. The F indicator will flash.
  5. Press the LOW key. The transceiver will now enter the repeater cross-band mode of operation.
  6. To cancel the operation and return to the VFO mode, press the VFO key.
Figure 2
                              rear of radio
         ------------------------------------------------------
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         !               o  o                                 !
         !               o  o                                 !
         !               o  o                                 !
         !               o  o                                 !
         !  __add__________Xo                                 !
         !  i               o                                 !
         !  i               o                                 !
         !  i                                                 !
         !  i ooooooooooooooooooooooooooooooo                 !
         !  i                                                 !
         !  -------i                                          !
         !         i                                          !
         !         Xo@o                                       !
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         !         ooooooooooooooo                            !
         !       oooooooooooooooooooo                         !
         _____________________________________________________
         mic plug    (radio bottom)
         (Jumper wire from X to X)

TM-701 transmitting and receiving from 136-175MHz


The Kenwood TM-701 A is capable of transmitting and receiving from 136-175 MHz. and from 340-512 MHz. when the following mods.

Cut the GREEN jumper wire on the Control PC Board behind the front panel.
The control PCB # is X57-3350-00. Add Diode D207 and D 209 (1ss181 or equiv) a 1n914 should work fine. Anode goes to the switches and the cathode to the IC (IC201).

2. Reset the microprocessor by holding in the "MR" key as the power is turned on.

to access the Control PCB:
  1. remove top bottom covers.
  2. remove knobs pulling them straight off of the front panel.
  3. Remove plastic faceplate.
  4. remove 4 screws on front panel metal spacer and remove panel.
  5. remove plastic panel/LCD by pulling straight off of the rig toward front.
  6. remove the 3 screws from the Control PCB and pull straight off of the chassis.
  7. Diodes mount on the back of the PCB at S205 and S209. The Andoe goes toward the switches and the cathode goes away from the switches.
    D209 goes to S205 (TONE switch)
    D207 goes to S209 (MR switch)
    D208 goes to S204 CAUTION remove D208 only if you want to change the split from +- 5 Mc to +- 1.6 and - y6 Mc (european split).
    replace all parts in reverse order. There is no RF circuit adjustments needed for this mod.

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