Can We Subtract 256 From 352? 352 - 256; Can We Subtract 64 From 96? 96 - 64; Can We Subtract 32 From 32? 32-32=0; Yes - Ramsey Electronics FX-440 Manual

Can we subtract 256 from 352? YES (Therefore: 256 diode}
352 - 256 = 96
Can we subtract 12B from 96? - NO (Therefore: NO 12B diode}
Can we subtract 64 from 96? YES (Therefore: 64 diode}
96 - 64 = 32
Can we subtract 32 from 32? YES (Therefbre: 32 diode}
32-32=0
As soon as we get a result of 0, we are finished, the remaining positions
are left empty (indicating a zero).
Let's check our results using this shortcut method:
On the previous page, we found the binary equal of N = 35,6BO was:
1 0 0 0 1 0 1 1 0 1 1 0 0 0 0 0
And, just now, we find the binary value of N to be:
1 0 0 0 1 0 1 1 0 1 1 0 0 0 0 0
We see that this way leads us to a correct result also. We could go on
and on with shortcuts and tips. For example, we can just know in our
heads that the "1" position is used only for frequencies with 12.5 KHz
spacing. The most important thing is simply to become comfortable and
accurate in converting N to its binary equivalent.
THE
RXfTX
OFFSET PROGRAMMING MATRIX
Diode placement in this matrix follows the same binary number principles
as used for frequency programming. This matrix is connected to the 16
programming inputs of U6 through the four binary adders (U7-U10).
Fewer programming positions are provided on the board simply because
there is no practical use for extremely large or very tiny frequency
offsets. The 2 to BK range provides plenty of flexibility for non-standard
channel spacing.
U7 through U10 are called • 4 bit" binary adders because they each can
handle four binary addition operations. For each bit, there are A and B
inputs and one S (sum) output. Examine the schematic diagram closely,
and you will see that all the frequency programming lines are connected
to •A" inputs and all offset lines go to • B" inputs. Notice further that the
binary positions of both matrixes correspond to each other exactly: the
BK offset position goes to 81 of U7 and the BK frequency programming
position goes to A 1. Their sum appears at S1 (pin 1) and goes to U6. And
so forth for all the other binary positions of both matrix areas.
We made it very easy for you to set up the required receiver frequency
and standard 5 MHz transmit offsets. Simply insert diodes correctly in the
holes marked by circles, solder, and you're in business.
FX-440
Assm. 55