Ramsey Electronics FZ-146 Specifications download pdf (Page 110)

FX 146 • 110

Stage H: FREQUENCY PROGRAMMING:

Understanding and Building the Diode Matrix

The labeling of the 16 parallel programming inputs of U6 should have a

familiar ring to anyone with at least some understanding of computer

principles, which should include all of us by now. Even though our desired

"N" number is a five-digit decimal number, it is programmed as a "16 bit"

BINARY number.

Binary numbers can be as big as you like, but we get there by counting on a

base of two, either 1 or 0, yes or no, on or off. This is, of course, the

foundation for all digital circuitry.

The programming inputs of your FX transceiver synthesizer can be set for

any frequency in its range, using the correct "N" number, by means of the

diode programming provided with your kit, or with simple switches, or by

digital switching circuitry, or by a dedicated microprocessor circuit, or by a

control circuit controlled by the same computer you use for packet, etc.

We will cover only the diode programming approach with some brief

suggestions on externally controlled switching. It is very intentional on our

part to leave innovative programming schemes up to FX transceiver users,

because there's no single best way to do it for everybody. Our job was to

break the price barrier on a practical, state-of-the-art VHF transceiver and

make it highly useful for most operating patterns.

You have easy front-panel selection of ANY 12 frequency pairs and never

need to buy a crystal. Nor should you ever need factory service. THAT is

what this transceiver is all about!

There are several methods for quickly finding the required binary code for a

particular frequency and its "N" number:

1. Descending Subtraction (see Programming Worksheet)

2. Printed reference lists (see Popular 2 Meter Band Pairs)

3. Computer programs (see our sample BASIC program)

We recommend strongly that you fully understand how to make the

"attempted descending subtraction" calculation yourself, because that is

your ONLY means for checking the accuracy of printed information,

computer programs or the operation of experimental programming circuits.

Let's walk through the programming of 146.52 MHz, which is the national

Simplex Calling Frequency and is also the demonstration and alignment

standard for the FX-146 model. You'll see exactly what we mean by

"descending attempted subtraction." Also, this is how the model BASIC

program for diode programming included in this book is structured.

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Ramsey Electronics FZ-146 Specifications Page 110