IC24AT additional features (miscellany)
                =======================================

(Part 3)

FREQUENCY EXPANSION
~~~~~~~~~~~~~~~~~~~
I received the following mods for 24AT out-of-band from a very reliable
source (although they don't specify RX only or RX/TX), for 75-195MHz,
200-490MHz, and 740-960MHz.

1.  Remove diode D8  [see figure below]
2.  Attach diode D7 [I believe this is already equipped]
3.  Attach diode D12
4.  Remove diode D13
5.  Simultaneously hold "LIGHT", "B", and "#" keys and turn the power on.
6.  Simultaneously hold "LIGHT" and "3" keys and turn the power on.
    This enables the 100MHz frequency digit entry.

 ________________
|                |
|                |
|      CPU       |
|                |
|                |
|                |
|________________|


                    o     o  o      D7 lower left pin is
                  [D7]    [D8]         anode of one diode,
                  o  o      o          lower right is cathode
                                       of the other.  Top pin
                          o  o         is common
                          [D12]
                            o       D12 upper pins are cathodes
                                        of diodes, lower is
                                        common anode.

              __I_     __I_             See text
              |  |     |  |
         D13  |__|     |  | D14
              |/\|     |  |
              |  |     |  |
              |__|     |__|
                I        I

WARNING: I have NOT tried the hardware mods and cannot vouch for them, so
proceed at your own risk!
>
Steps 5-7 don't seem to have any effect on a 24AT without the correct
hardware mods.  BTW, this has been attempted on 2 units with serial numbers
around 1000 and mid-1100's, neither of which worked.

Additionally, diodes D7, D8, and D12 are surface mount components.  They
contain 2 diodes connected to 3 pins.  Diodes D7 and D12 are different
configurations.  I believe D8 and D12 are different, so I wouldn't put the
removed D8 in the spot for D12.  Since they are surface mount, removal of D8
may not be all that difficult for those with steady hands and a fine low
power soldering iron, but adding D12 would be a bear.  I know of no reason
that small discrete diodes couldn't be used in for D12.  D13 is a small but
standard axial diode, and can be easily cut.

PROBLEMS
~~~~~~~~
Each amateur band from 6m to 23cm was tried.  The PLL doesn't lock up at
either end.   Another negative is the frequency step on 220 doesn't allow one
to hit each possible repeater slot.

Cont'd in part 4

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