QRP Labs QCX-mini CW, Руководство по сборке, Страница: 23 / 121

3.2 Wind and install transformer T1
This is the only really tricky piece of the
assembly: the receiver input transformer T1.
Follow these instructions carefully, it is
tricky but quite feasible if you go step by
step.
This is the FIRST step because it is
easiest to do the installation when there
are no other components nearby.
In the end, you are going to end up with an
installed transformer which hopefully looks
something like the photo (right, shows 40m
version).
This transformer has FOUR windings.
Three identical short windings, and one long
winding. There are therefore eight wire ends, which must all be soldered into the correct
holes on the PCB, and with the enamel properly removed.
Here are two diagrams which enumerate each of the windings, wire endings and holes on
the PCB, on both the layout diagram and on the circuit (schematic) diagram. It should help
to explain diagrammatically which wires must go where.
On the following page is a diagram hand-drawn by Ed WA4MZS (thanks Ed!) which may
also clarify the construction and installation of T1.
The four windings on T1 must all be in the same “sense”. There are two ways to wind
toroids. You might call them left-handed and right-handed; clockwise and counter-
clockwise; whether the wire goes through the toroid from top to bottom, or from bottom to
top. Whatever you call it, all the four windings have to be the same, to be sure to get the
phasing to the quadrature sampling detector correct.
(Technically, only the secondary 1 and secondary 2 have to be in the same sense; but it is
simpler to just wind everything the same way).
QCX-mini assembly Rev 1.05
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