copied from the Internet:
From: rosenblg@cmcl2.nyu.edu (Gary J. Rosenblum)
Subject: how to program the ICOM-U16
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If the U16 has been made programmable by moving a jumper:

Try holding FUNCT down and entering 159357.
It's now in prog mode.  Exit with FUNCT-CLR.
Function + 159357  (Enter program mode)

Function + 1    Encoder tones (1-37) 1=67.0,2=71.9,3=74.4,4=77.0,5=79.7,
                                6=82.5,7=85.4,8=88.5,9=91.5,10=94.8,
                                11=100.0,12=103.5,13=107.2,14=110.9,
                                15=114.8,16=118.8,17=123.0,18=127.3,
                                19=131.6,20=136.5,21=141.3,22=146.2,
                                23=151.4,24=156.7,25=162.2,26=167.9,
                                27=173.8,28=179.9,29=186.2,30=192.8?,
                                31=203.5,32=210.7,33=218.1,34=225.7,
                                35=233.6,36=241.8,37=250.3

         + 2    Decoder tones (1-37)
         
         + 3    ?
         
         + 4    Delta + / Delta - offset, 5 digits
         
         + 5    Frequency, 5 digits (400MHz +)
         
         + 6    ?
         
         + 7    Sch. Ch. numbers. Allows alias ch numbers.
         
         + 8    Transmit timeout enable.
         
         + 9    TI, Transmit Inhibit
         
         + SCAN Priority Scan/Ch Scan
         
         + S.CH Channel Masking
         
         + CLEAR   End progamming mode

---------------------------------------------------------------------------
Channel select:  Standard method (up/down arrows or CH# + [ENTER])
Frequency:  Hold [FUNC], Press [5], enter 6 dig freq, [ENTER], release
            [FUNC]
Rx CTCSS:   Hold [FUNC], Press [2], enter 2 dig code, [ENTER], release
            [FUNC]
Tx CTCSS:   Hold [FUNC], Press [1], enter 2 dig code, [ENTER], release
            [FUNC]
Offset Freq:  Hold [FUNC], Press [4], use [#] for up offset, [*] for
              down offset, then enter freq to offset by (ie: [#] [0] [0]
              [0] [0] [0] for no offset, [#] [0] [5] [0] [0] [0] for the
              standard +5MHz UHF offset), [ENTER]
Timeout Timer: Hold [FUNC], [8], Release [FUNC]
Tx Inhibit: Hold [FUNC], [9], Release [FUNC]
Special Channel Number: Hold [FUNC], Press [7], enter the special
channel number (17-99), [ENTER], Release [FUNC]l
Data Transfer MASTER: Hold [FUNC], [BEEP], Release [FUNC]
Data Transfer SLAVE:  Hold [FUNC] with power off, turn on, release
[FUNC]

-- 
Gary J. Rosenblum	
UNIX Systems Manager			rosenblg@nyu.edu
New York University			gary@nyu.edu
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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 for your license.  WA2ISE
/EX