Kyodo KG110 alias Nokia BSR450 channel control Kyodo KG110 base station radio has separate transmitter and receiver modules with MC145146 synthesizer in both modules. The master oscillator is in the receiver module and the 750 kHz reference signal is fed to the transmitter module. The PLL IC has a four bit parallel interface for the frequency control. The A, N and R registers are programmed with a sequence of 8 nibbles. The data is stored in a 2764 EPROM, but only the four lowest data bits are used. Each channel data occupies 8 consecutive bytes in the EPROM. The three lowest address bits are stepped continuously with a counter circuit that is clocked with the 750 kHz reference. The upper address bits are used to select the channel. As the lowest bits are stepped continuously the synthesizer frequency is changed almost immediately after the channel select bits are changed. The Kyodo manual lists the channel control data for each frequency, except 420-440 MHz. So for amateur use the data must be calculated and programmed manually. This is quite tedious so I made a small program that calculates the data from a frequency list and programs it into two binary files. The channel list must be in file "BSR450.CHN" with the format as shown in the sample file. You can edit the table as long as the columns stay intact. The channel number is given for each entry, so the order of the list does not matter. When the program (BSR450.EXE or BSR450.BAS under Quick Basic) is run it stores the channel EPROM data in two files, BSR450RX.BIN and BSR450TX.BIN. The images can then be programmed onto two EPROMs and swapped in the RX and TX modules, respectively. If you need more than 128 channels, you have to control the upper address bits (A10, A11 and A12) which are normally tied to ground. So some surgery is needed. The channel step is fixed at 12.5 kHz. If other steps are needed, the reference divider (R-register) value must be changed in the program source code. (12.5 kHz = 60, 10 kHz = 75, 5 kHz = 150 etc.) 73 de Arto, OH2BGN