QRP Labs QCX-mini, Руководство по сборке

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Signal Generator
The signal generator mode was also discussed in the operating manual section. The signal
output is taken from the Clk0 or Clk1 output of the Si5351A (there are no pads for this).
Care should be exercised not to draw excessive load (e.g. short circuit) from these pins,
which could damage the Si5351A. It will be very difficult to replace a damaged Si5351A.
Self-test of Signal Generator and Frequency Counter
Note that once the Signal Generator has been activated by scrolling to the Signal Generator
menu item, and pressing the “Select” button to enable it – the Signal Generator remains
active on the set frequency, until you press the “Exit” button and leave the Test Equipment
menu.
Press the “Select” button to enable the signal
generator; an underline cursor appears under
the digit that will be tuned by the rotary encoder.
Adjust the signal generator to produce a
frequency some way under 8MHz. Let’s say,
6MHz. When you leave edit mode, by pressing
the “Select” button until the cursor disappears
off the right side of the 1’s digit, OR by pressing
the “Exit” button, then the cursor will no longer
be shown on the display. Turning the rotary
encoder 1 click anticlockwise shows menu 9.5,
the frequency measurement. Now if you connect
a wire from the FREQ input to the CLK0 output,
you will measure the signal generator’s
frequency. This is shown here in the photograph (right, original QCX not the QCX-mini);
clearly the 2kHz low reading indicates I have not calibrated the 27MHz reference value and/
or the 20MHz system clock value!
In the photograph, the white wire shown looping around the rotary encoder connects the
FREQ pin (just under the “M” character of the LCD, in the photograph) to the Clk0 output
pin (just under the “z” character of the LCD).
This is a convenient way to get the frequency counter to verify the correct operation of the
signal generator (and hence the Si5351A synthesizer). The signal generator output is
available at both the Clk0 and Clk1 pins, hence you can test them both.
4.17 5V voltage regulator
5V for the
microcontroller,
Quadrature Sampling
detector chip, LCD
module and IC3 (quad
NAND gate) is provided
by IC11, a AMS1117-5.0
5V 1A voltage regulator.
Note that the input is
protected against
QCX-mini assembly Rev 1.05_Fr
117