QRP Labs QDX, Assembly And Operating Manual

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2. Assembly
2.1 General guidelines
Assembly of this kit is quite straightforward, most components are SMD and have already been
pre-assembled by the PCB factory. The usual kit-building recommendations apply: work in a well-
lit area, with peace and quiet to concentrate. S
ome of the other semiconductors in the kit are
sensitive to static discharge. Therefore, observe Electrostatic discharge (ESD) precautions .
And I say it again: FOLLOW THE INSTRUCTIONS!!
Don’t try to be a hero and do it without instructions!
A jeweler's loupe is really useful for inspecting small
components and soldered joints. You’ll need a fine-
tipped soldering iron too. It is good to get into the habit of
inspecting every joint with the magnifying glass or
jeweler's loupe (like this one I use), right after soldering.
This way you can easily identify any dry joints or solder
bridges, before they become a problem later on when
you are trying to test the project.
You could also take photos with a mobile phone, and use
the phone’s zoom features to view the board in detail.
Triple check every component value and location BEFORE soldering the component!
It is easy to put component leads into the wrong holes, so check, check and check again! It is
difficult to de-solder and replace components, so it is much better to get them correctly installed
the first time. In the event of a mistake, it is always best to detect and correct any errors as early
as possible (immediately after soldering the incorrect component). Again, a reminder: removing a
component and re-installing it later is often very difficult!
Please refer to the layout diagram and PCB tracks diagrams below, and follow the steps carefully.
Use of a good quality soldering iron and solder is highly recommended for best results!
The following diagrams show the PCB layout and track diagrams of the QDX.
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.
NOTE: the capacitor lead spacing on the PCB is 0.1-inches (2.54 mm) and most of the capacitors
are sized appropriately for this. From time to time, due to availability constraints, we may have to
use capacitors with 0.2-inch lead spacing (5.08 mm); this is not a mistake, it is just due to
component availability. In this case simply use a pair of long-nosed pliers (etc) to straighten out
the wires and make them spaced for the 0.1-inch pads.
QDX assembly Rev 1.00
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