ICOM 02,03,04 SERIES MATRIX INFORMATION ======================================= All cathodes down (to R20 or R21) | | | | |\ | | | R21 ----|----|----|----|---- R21 ----|--\-|----|----|---- |\ |\ | |\ | | | |\ R20 ----|--\-|--\-|----|--\- R20 ----|----|----|----|--\- | | | | | | | | 118.00 init 220.00 init 0 - 330 range 220.00 - 224.99 range ********* | | |\ | | |\ | | R21 ----|----|----|--\-|---- R21 ----|----|--\-|----|---- | | | |\ | |\ | | R20 ----|----|----|----|--\- R20 ----|----|--\-|----|---- | | | | | | | | 220.00 init 430.00 init 0 - 699.99 range 430.00 - 339.99 range *********** | | | | | | |\ | R21 ----|----|----|----|---- R21 ----|----|----|--\-|---- |\ |\ | | |\ | | | R20 ----|--\-|--\-|----|---- R20 ----|--\-|----|----|---- | | | | | | | | 440.00 init 144.00 init 327.68 - 627.68 range 0 - 699.99 range *********** | |\ | | | |\ | | R21 ----|----|--\-|----|---- R21 ----|----|--\-|----|---- | | |\ | |\ | | | R20 ----|----|----|--\-|---- R20 ----|--\-|----|----|---- | | | | | | | | 140.00 init 144.00 init 140.00 - 151.99 range 144.00 - 147.99 range *********** This represents a few of the matrix combinations possible for the Icom 02/03/04 series of radios. In addition the placement of a diode from R10 to R23 (cathode at R23) (Icom type 'D' diode at schematic position D405) will allow direct 10 MHz entry from the keypad. This works on newer serialed radios also. **** NOTE !!! **** Icom has bowed to pressure from the commission and made changes in software to disallow transmit out of band. However, receive modifications STILL WORK. On the 02, simply: remove the diode marked on the schematic as 402 (D2 on the board). On the 04, remove the diode at 402 and connect a 1N4148 type diode between R11 (anode) and R20 (cathode). Make these modifications at your own risk. I do not recommend you try experimenting unless you are willing to accept the consequences of your actions. For further information see my article in 73 Magazine. June 1986. My address from that article has been corrected to: Tim Wright AL7DS 704 N. 7th Ave. Maywood, Il. 60153 (Downloaded from GB7SYP)