QRP Labs QCX-mini CW, Руководство по сборке, Страница: 18 / 121

Tracks shown in BLUE are on the bottom layer. Tracks shown in RED are on the top layer.
There are only two layers (nothing is hidden in the middle). Not shown in this diagram are
the extensive ground-planes, on both sides of the board. Practically everything on both
layers that isn’t a RED or BLUE track, is ground-plane! The two ground-planes are
connected at frequent intervals (not more than 0.1-inches) by vias. This is the kind of layout
I have done previously for a quad-band GSM device operating at up to 1900MHz… it is
probably overkill in an HF transceiver… but if you can, why not! I used to say often that you
can never have too much supply line filtering and decoupling, and never have too much
shielding. Both these statements don’t apply so conveniently to kits as they do to homebrew
projects. In a kit every decoupling capacitor has a cost in both money and PCB area (which
also means more money). Shielding is even more difficult and expensive. So shielding and
decoupling should be applied where needed only! But ground-plane – well that’s another
story. It’s free, and without drawbacks – so why not, let’s just put it everywhere.
All components on the main PCB are installed on the top (component side) of the PCB and
soldered on the bottom (solder side) of the PCB. On the display PCB the 2x5-pin header
connector is installed on the reverse side so refer to the assembly manual steps very
carefully.
Take care when installing integrated circuits. All through-hole integrated circuits are
supplied by the manufacturers with their pins bent a little wide. You need to carefully bend
the rows of pins of the ATmega328 microcontroller together a little, in order to fit it into the
28-pin IC socket.
The band-specific Low Pass Filter (LPF) parts are supplied in a separate LPF kit bag.
In the construction for some bands, not all of the capacitors supplied in the kit are used. Do
not be alarmed if you have a few components left over at the end!
Wind the L1-3 inductors with the enameled copper wire supplied in the LPF kit bag. Wind
the other inductors (L4 and transformer T1) using the wire supplied in the main kit bag.
The component colour coding of the layout diagram at every step of the assembly
instructions is as follows (kind of: components past, present and future):

Components shaded grey have already been installed

Components shaded red are the ones being installed in the current assembly step

Components shaded white are the ones which have not yet been installed
The following photographs show the final assembly. You can keep these photographs in
mind when assembling the kit, they will give you some idea of how the kit fits together and
help avoid assembly errors.
QCX-mini assembly Rev 1.05
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