TM-221A MOD

This modification will allow you to change the transmit and receive
characteristics of your TM-221A quite significantly from its current status.
Some of modes you will have access to will be somewhat useless as they
require other modifications to be carried out in other parts of the radio.
These would usually have been done by the manufacturer at assembly depending
on where the radio was to be marketed in the World.
Eg. Europe / England / Australia / America / Japan etc etc.
In no way do I condone transmiting outside the approved Amateur Bands as
layed down by the DOTC. What you do with the radio is your bussiness, I am
merely showing you ways to increase the versatility of your radio.


Resistors   RX Range TX Range  AO  FS  SH  RE  SC  CT  TO  MS  MT
22 23 24 25
0  0  0  0   138-174  138-174  N   B   Y   M   Y   AL  Y   --  --   *1
0  0  0  1   138-174  138-174  N   B   Y   M   Y   AL  Y   --  --   *2
0  0  1  0   144-146  144-146  N   B   Y   M   Y   AL  Y   --  --   *3
0  0  1  1   138-174  138-174  N   B   Y   M   Y   AL  TX  --  --   *4
0  1  0  0   144-146  144-146  N   B   Y   M   Y   AL  TX  --  --   *5
0  1  0  1   154-174  154-174  N   A   Y   Y   Y   Y   Y   --  Y    *6
0  1  1  0   138-148  138-148  N   A   Y   Y   Y   Y   Y   --  Y    *7
0  1  1  1   138-174  138-174  N   A   Y   Y   Y   Y   Y   --  Y    *8
1  0  0  0   138-174  142-152  Y   A   Y   Y   Y   Y   Y   --  Y    *9
1  0  0  1   138-174  144-148  Y   A   Y   Y   Y   Y   Y   --  Y    *10
1  0  1  0   138-174  138-174  Y   A   Y   Y   Y   Y   Y   --  Y    *11
1  0  1  1   142-152  144-148  Y   A   Y   Y   Y   Y   Y   --  Y    *12
1  1  0  0   144-148  144-148  Y   A   Y   Y   Y   Y   Y   --  Y    *13
1  1  0  1   118-174  138-174  N   A   CA  AL  Y   Y   Y   CF  Y    *14
1  1  1  0   118-174  144-146  N   A   CA  AL  Y   Y   Y   CF  Y    *15
1  1  1  1   144-146  144-146  N   A   CA  AL  Y   Y   Y   CF  Y    *16
-----------------------------------------------------------------------
0 = Not Present  1 = Present  N = No  Y = Yes  M = Momentary
AL = Alert  TX = Transmit  CA = Call  CF = Call Frequency
A = 5/10/15/20/25 Khz Steps  B = 5/10/12.5/15/20/25 Khz Steps
AO = Auto Offset  FS = Frequency Steps  SH = Shift  RE = Reverse
SC = Scan  CT = CTCSS  TO = Tone  MS = M.IN Shift  MT = M.IN Tone


CF sets the Call Frequency which is then the Frequency that is loaded into
the VFO each time the Call function is used.

TX transmits a set sub-audible tone of 1750 Hz.  The tone cannot be changed.

*1 thru *5 receive nothing and transmit very little due to other changes
required in the rig.

*6 thru *16 receive and transmit in the Amateur Band as well as out of it,
although retuning of the RF stages would be required if transmission out of
the Amateur Band were to take place at more than the odd transmission!!

                       ****** NOTE ******
Transmission outside the Amateur Band by Licenced Amateurs is strictly
illegal unless prior permission is obtained from the DOTC.

Hope all this information is of some use to you in increasing the capabilitys
of an already great rig.
                                   GREG VK3TDR.
                                   WERRIBEE.


Resistors R22,23,24 & 25 can be found on the rear of the main display board.
If you wish to gain access to these and properly identify them the service
manual would be of great advantage.  Alternatively I can provide you with a
diagram of the relavent sections which will show you precisely where they are
located within the rig.  All the best.
