QCX assembly Rev 1.08
123
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 synthesiser). The signal generator output is available at both
the Clk0 and Clk1 pins, hence you can test them both.
5.17
5V voltage regulator
5V for the microcontroller, Quadrature
Sampling detector chip, LCD module and
IC3 (quad NAND gate) is provided by
IC11, a 7805 5V 1A voltage regulator.
Note that the input is protected against
reverse polarity by D3, a Schottky diode
type 1N5819. This also drops the voltage
by 0.3 to 0.4V, which has the effect of
reducing the output power.
If you are brave, and confident that you will NEVER connect power to the radio with reversed
polarity, you can omit this diode and fit a jumper wire over it.
6. Fault-finding
6.1
Blank LCD or blocked LCD
If your LCD screen looks like either of these, then it is a sure sign that you have not adjusted the
contrast trimmer potentiometer R47.
6.2
No backlight at all
If there is no LCD backlight at all, check that you have installed R48, and also check that you have
properly installed the LCD connector between the main PCB and the LCD module.
Содержание QCX 5W CW
Страница 9: ...QCX assembly Rev 1 08 9...
Страница 10: ...QCX assembly Rev 1 08 10...
Страница 12: ...QCX assembly Rev 1 08 12...
Страница 26: ...QCX assembly Rev 1 08 26 3 19 Install 20MHz crystal XTAL1 The engraving on this crystal is 20 000...
Страница 50: ...QCX assembly Rev 1 08 50...
Страница 105: ...QCX assembly Rev 1 08 105...