Bulletin:  AL5140
Vendor:    Alinco / DR-600
Subject:   Installing the 800MHZ antenna input to UHF receiver


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.

REMEMBER:  These modification are to be preformed at your own risk.
           This rig is very compact and probaby won't give you a
           second chance if you screw up. SO BE CAREFUL.

Good Luck  /  73 de Ron  WB4HFN@KB4N.NH