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Kenwood TH-D72 Extended TX mod

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  #1  
Old 12-10-2010, 01:22 PM
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Default Kenwood TH-D72 Extended TX mod


Here is how you modify the TH-D72 to transmit out of the 2m/440 band:

Take the radio apart by following this sequence of steps:
  1. Remove the battery.
  2. Remove the antenna and pull off the top dial knobs
  3. Remove the two screws on the back.
  4. Unlatch the rubber ports cover from the post on the back. Use a small screwdriver to slip under and it just pops off.
  5. Pull the case up and off.
  6. Detach the rubber button cover from the front and set it aside.
At the bottom front of the circuit board, below the number button pads, there is a small diode labeled D729. Remove that diode shown in this pic:



Remove the screw that holds the LCD display in place and gently lay it over. Underneath the display there is a row with three diodes labeled 1,2,3 near the speaker ribbon cable.

Remove diode D730 (labeled 1)

This is how the 3 diodes should be after mod:

1 - removed
2 - removed (USA version does not have it)
3 - must remain in itīs place (that means DO NOT remove it!)

Reassemble the radio and perform a FULL reset by going into the Auxilliary menu.

Transmit range is now:
136-173.995 MHZ
410-469.975 MHZ


note: Thanks to XE1BRX for updating the original version of this mod resulting in greater TX frequency range.


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Old 12-10-2010, 01:56 PM
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any idea what the other diode is for?

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Old 12-10-2010, 02:14 PM
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Quote:
Originally Posted by Brlux View Post
any idea what the other diode is for?
Nope, I tested the radio with and without that other diode and didn't find any difference Without a schematic, it's impossible to tell what it does.

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Old 12-10-2010, 02:18 PM
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So when removing the second diode you did not notice any change in TX range or new features like crosband repeat enabled? To bad, I wonder what it is supposed to do. Wasn't there a radio that had to be moded like this to allow crosband repeat? I think it was the European version of a radio.

Last edited by Brlux; 12-10-2010 at 03:34 PM.

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Old 12-10-2010, 08:47 PM
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I tried this mod, and after resetting the radio from the Aux menu, as well as the F-Power on option, the radio cleared it's memories properly, but this did not seem to the enhance the UHF or VHF transmit range.
Any other tricks ?

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Old 12-13-2010, 10:42 AM
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Did you do the full reset, or VFO only? You need to do the FULL reset. Also, make sure your radio isn't in the auto repeater offset mode when trying to TX out of band. I thought the 440 expansion didn't work at first until I paid attention to the offset that was being activated, LOL.

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Old 12-13-2010, 06:12 PM
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did the reset multiple times, and 449.995 is the highest area that it will transmit, in simplex mode..

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Old 12-20-2010, 07:31 AM
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I was just on the mods.dk site and the mod they show for the D72 is quite different. Admittedly it is for the E version, but their are 3 diods in a row on a different board. Any thoughts on this?

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