From: levin@cosmic.physics.utah.edu (Chris Levin)
 
I just got the info on how to modify the Alinco DR-600.  I have
activated these mods and they seem to work fine.  Here they are:
 
Mod 1 - Activate 108 - 142 MHz and 810 - 998 MHz Receive
--------------------------------------------------------
 
Remove head unit from radio and open it up.
 
Inside you will see a red and blue wire.
 
Cut the red wire.
 
Open the main unit and attach a wire to CN-205.  This will be
your antenna for 810-998 MHz.
 
Close everything up.
 
Reset the CPU by holding down the FUNC key while you turn the
radio on.
 
To use:
The VHF key toggles between 108-142 and 2m.  This toggle
only works in VFO mode.
 
The UHF key toggles between 810-998 and 70cm.  This toggle
only works in VFO mode.
 
 
Mod 2 - Extened tx/rx on 2m and 70cm
------------------------------------
 
Remove head unit from radio and open it. (2 screws on back)

Inside you will see a red and a blue wire.

Cut the blue wire.

Put everything back together.

Reset the CPU by holding down the FUNC key while you turn
the radio on.
 
You can now transmit and receive on the following freqs:
130-174MHz and 400-517MHz

==============================================================================
Subject : MODS For Alinco DR-600 Dualbander

The new Alinco DR-600 dual bander has a few modifications that may be
of interest to the ham community.  I performed the modification to my
radio without any problems.  The modifications include:

1)  Receive the aircraft band with an AM detector tuning 108-142MHZ
2)  Extended receive and transmit range on both bands.
3)  Allow access to receive the 810-998MHz band

Open Up AM Aircraft Band And Extend RX/TX Range
==============================================
A) To perform the first 2 modifications, remove the front panel from the
   radio by removing the 4 screws, there are two on each side of the
   radio along the front edge.
B) Unplug the control head from the main radio.  Remove the two screws
   holding the rear cover on the control head and pop off the rear cover.
C) Looking at the PC board you will see a red and green jumpers in the
   center of the board.  Remove both jumpers.
D) Reassemble the radio and reset the microprocessor.  To reset the radio
   turn OFF the radio, now push and hold the FUNCTION key and turn ON
   the radio.
E) The extended range both transmit and receive on VHF is 130-172MHZ and
   UHF is 400 to 519MHZ.
F) To access the AM aircraft band push the VHF button to select that
   band and then press the VHF button a second time. The radio will
   display "AM" next to the frequency readout and tune 108 to 142MHZ.
H) To access the 800MHZ band press the UHF button to select that band
   and then press the UHF button again to switch between the 70cm band
   and the 800 MHZ band.  At this point the 800MHZ band will receive but
   does not have an antenna connected to it, so in order to use this band
   the modification below is necessary.


Installing Antenna Connection For 800MHZ Band
=============================================
The radio will receive this band as shipped from the factory after the
above modification, however, there is NO ANTENNA connected to the input.
On the back of the radio you will notice three holes in the heat sink
next to the 70cm antenna lead.  You will need to add a third coax lead
through this hole and connect it to the 800MHZ input.  Remove the covers
from the radio and follow the 70cm coax into the radio.  The UHF portion
of the radio is located on the bottom half  of the radio.  Remove the RF
shield covering the transmit area by removing the 4 screws holding the
shield to the chassis.  You will notice a small coax cable going from
the transmit section to the receiver next the the 70cm antenna coax.
In the receiver section it plugs into a small connector soldered to the
board at a 45 degree angle.  Along the outside edge you will see another
connector of the same type labeled CM50, this is the 800MHZ input.  You
will need to solder a coax cable from this open connector, route it
through the transmitter section and then through the open hole in the heat
sink.  There is a nice channel cut in the chassis where the coax will
lay nicely so it won't get pinched when the RF shield is replaced.
I just soldered the end of the coax center conductor and then filed it
down to fit snugly in the socket. The coax shield is soldered to the
connector housing.  This is the best option for making the connection
unless you can find the proper connector for the socket.  I left about
6 inches of coax hanging out the back of the radio and installed a BNC
connector.  Any type of small diameter coax should work, I used a small
piece of RG-58.  The last step, reassemble the radio being careful to not
pinch the internal wiring.

I found the sensitivity between 810 to 889 to be execellent, varing
between .15 to .35 u/V.  Though it will receive between 810-998MHZ,
outside the 810 to 889 range the sensitivity is extremely poor. The
aircraft band, 108-142 is very sensitive accross the entire band.

