TW-4000 wide frequency range on VHF
-----------------------------------

On the back of the CPU assembly, (part of the front panel assembly),
there is a wire jumper (sort of a loop of wire between two pads on
the board).  If you clip this wire, and reset the CPU, the '4000
will RX-TX from 141.0 Mhz to 150.995 Mhz.  There is no change on
UHF.

Let me know if this helps.


-- 
 Keith McQueen, Wicat Systems Inc. , (801)224-6400      | My opinions are |
 Packet:      n7hmf @ nv7v.UT.USA.NA                    | all mine...     |
 Internet:    keithm@wicat.com                          | ...so there!    |

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KENWOOD TW-4000 A  frequency range:

The TW-4000A mobile transceiver can be converted from US to Europe (or back)
by changing a few diodes and one crystal. After the change, the UHF section
and "430" circuits may have to be realigned. Note that the required crystal
may only be available in the country in which operation is desired, contact
KENWOOD for ordering information (or contact your friendly neighborhood
crystal factory, the crystals are 20pF serial resonance).

Modification procedure:

1. Disassemble the radio by removing top and bottom covers as well as the
   screws holding the front panel.

2. Disassemble the PLL unit by removing the cover, then removing the circuit
   board

3. Locate and replace crystal X3 in the PLL unit. The frequency required for
   operation in the U.S. (UHF 440-450 MHz) is 33.6446 MHz, for operation
   elsewhere (430-440 MHz) it is 32.8125 MHz.

4. Reassemble the PLL unit.

5. Locate the diode matrix on the CONTROL ASSEMBLY (located on the back of
   the front panel. Remove the Lithium battery (some diodes are obscured by
   the battery).

6. Move the diodes in accordance with the following layout (no additional
   diodes are normally required):
   (X denotes an installed diode)

   o o o   o o o o
       X   X X        For U.S. operation
   o o o   o o o o
   1 2 3   (see below)

   o o o   o o o o
   X       X   X      For European operation
   o o o   o o o o
   1 2 3   (see below)

   Diode in position 1: 430-440 MHz, 7.6 MHz repeater offset
   Diode in position 2: 430-440 MHz, 5.0 MHz repeater offset
   No diode in position 1 OR 2: 440-450 MHz, 5.0 MHz repeater offset
   Diode in position 3: Wide coverage VHF
   No diode in position 3: VHF coverage 144-148 MHz
   Other diodes:  function unknown...

7. Reconnect the litium battery and reassemble the front panel.

8. Check out correct operation using UHF signal generator, dummy load,
   wattmeter and frequency counter. Adjust TC7 on the PLL UNIT for exact
   frequency as shown on the dial. Adjust HB(A) and HB(B) on the RX-TX unit
   for optimum receiver sensitivity at 435 MHz.
   Adjust HB(D), HB(E), TC5 and TC6 on the RX-TX unit for maximum output
   power.
   If RX sensitivity and transmitter output are satisfactory without
   retuning, DO NOT fumble with the RX-TX unit!

9. Reassemble the transceiver. Modification is completed.

So, be careful and good luck!  Questions? DL1MEN @ DB0CZ