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Subject: TM-742/(942?) Control Unit X53-346X-XX ***B/2** Mod
From: Steve Lampereur 
Date: Sun, 25 Apr 1999 17:07:36 EDT

I have the TM-742 with a Control Unit X53-346X-XX ***B/2**

Procedure:
1. Remove the bottom cover of the transceiver by removing the 4 screws on
the bottom of the cover and loosening the 4 screws on the side of the
unit.
2. Orient the radio so the bottom is up and the front display is near
your chest. Near the front display area you will find an metal cover over
the a section
of the board, remove the two screw that hold it down in front.  It will
now be necessary to bend the metal cover up to gain access.
3. Locate the grouping of 473 chip resistor pads on the left, above the
chip labeled 2R7


This is what the [473] chip resistors grouping look like:      
----------+----------  
             | X X X
----------+----------
o o o o | o o o o  
----------+----------  
X X X X |           X   
----------+----------  

1 2 3 4   5 6 7 8

Here is what I have read pertaining to the TM-742 w/ Control Unit
X53-346X-XX *A/2*
Old version mod, per JP1LRT & N8QXP:
Make short circuit with middle line and lower line on all pads
New version mod, per JP1LRT & N8QXP:
Short the upper part of pad 8, & the lower of pad 5.
Universal mod TM-742/942, per VE2PAL:
Move the [473] chip resitors on pad 4 up, & chips 7 & 8 down.

None of these worked for me with the B/2 contol head.
So I figured this out myself.  

Short the lower part of pad 7.  No need to reset the radio, it does that
automatically.
The automatic repater offset will be disabled.

After the mod:
28  Mhz Band:   RX:   18.0 thru  54.0 Mhz
                            TX:   26.0 thru  45.0 Mhz
50  Mhz Band:   RX:   40.0 thru  90.0 Mhz
                            TX:   46.0 thru  76.0 Mhz
144 Mhz Band:  RX/TX:  136.0 thru 174.0 Mhz
220 Mhz Band:  RX:  215.0 thru 260.0 Mhz
                             TX:  215.0 thru 235.0 Mhz
440 Mhz Band:  TX:  410.0 thru 470.0 Mhz
1.2 Ghz Band    RX/TX: 1100.0 thru 1400.0 Mhz

Please note that these are theoretical ranges only. Not
all radios will be capable of tuning the entire range.

For informational purposes only.  I am not responsible for damages to
your radio.
kb9mwr@bigfoot.com
-

 

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