Ramsey Electronics FX-440 Manual page 40

N=21400+12.5 KHz= 1,712
Binary code for N = 1, 712
8192 4096 2048 1024 512 256 128 64 32 16 8 4 2
0 0 0 1 1 0 1 0 1 1 0 0 0
You'll see this is the number programmed into the Receive offset matrix
line.
EXAMPLE 3. TVVO'S COMPLEMENT WITH CARRY
For illustration purposes, we'll pick an odd-ball offset such as 1.6 MHz. In
this case N=1,600+12.5 KHz= 128.
Binary code for N = 128
8192 4096 2048 1024 512 256 128 64 32 16 8 4 2
0 0 0 0 0 0 1 0 00000
Invert all bits:
1 1 1
1 1
Add 1:
Sum at '2' bit position, carry 1
Sum at '4' bit position, carry 1
Sum at '8' bit position, carry 1
Sum at '16' bit position, carry 1
Sum at '32' bit position, carry 1
Sum at '64' bit position, carry 1
Sum at '128', no carry needed
Final result:
1 1 1 1 1
1
1
0111111
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
1 0 0 0 0 0
1 000000
1 0 0 0 0 0 0 0
1 0 0 0 0 0 0
BASICS OF EXTERNALLY-CONTROLLED FX-TRANSCEIVER
FREQUENCY SWITCHING
The 12 front panel switched channels, with never a need for a crystal will
cover most applications generously. Yet many of us will want to figure out
ways for easy frequency-programming of still more channels, especially if
we do a lot of cross-country travel. Rather than endorse or illustrate any
particular scheme, of which there are dozens if not hundreds, we provide
here the most basic schematic information needed to set up any kind of
auxiliary switching correctly. The principles and requirements remain the
same whether you use
DIP
switches, toggle or slide switches, electronic
latching or go all out to build the mother of all diode matrixes. Make sure
whatever you build resembles electrically the diagram on page 40.
Ref. 38
FX-440