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.