Tuesday, October 20, 2009

Modification extend Frequency Icom IC 2N

MODification File For ICOM IC-2AT
---------------------------------
If you have studied the schematic diagram for this radio,
you will notice that pins 15 and 16 are not indicated on
the programmable divider chip IC1 (TC9122).
By simply connecting pin 15 thru a switch to pin 1, you will
be able to move the radio up in frequency by 10 MHZ.

Some of these radios were sold without covering 140-150 MHZ.
The modification for this extended coverage is described below:
1) Open up the radio and locate the FLEXIBLE BOARD, this connects
the thumbwheel switches to the MAIN BOARD.
2) At the MAIN BOARD end of the FLEXIBLE BOARD, add a jumper at
location C4. There should already be a jumper at location C2.
3) At the thumbwheel switch end of the FLEXIBLE BOARD, remove the
jumper which connects C3 and COM.
4) Reassemble the radio. Coverage is now 140-150 MHZ.(MARS/CAP)

Now, if you activate the switch described above, the radio will
now operate in the 150-160 MHZ range, after L3 adjustment,
described below.

OPERATION and L3 ADJUSTMENT:
----------------------------
1) Activate switch and dial up a known active frequency.
2) Adjust L3 until PLL locks up and radio begins receiving.
(you need an active frequency to tell when this happens)
3) To return to 140-150 MHZ, repeat above steps with switch off.


NOTES and DISCLAIMER
--------------------
1) Drill a hole in the case of the radio so that L3 can be
adjusted from outside of the radio.
2) The above information is presented for educational
purposes only, and is not an endorsement of any particular
practice.
3) This MOD has been in operation for 6 years with no ill
effects on the radio
4) This MOD courtesy N2MOD.
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Note: I haven't tried or verified this, proceed at your own risk. And
do not transmit outside of legal bands!