QRP Labs QDX, Assembly And Operating Manual

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2.8 Assemble and install transformer T1
Transformer 1 is wound on the BN43-202 binocular ferrite former, using the thick 0.6mm (AWG
#22) wire. This wire is also used for L14 so do not use all of it on the transformer. \
The transformer has two windings, both 3 turns. The three-turn primary winding has a center-tap.
In the nomenclature of binocular cored transformers, “1 turn” means the wire passes through both
sets of holes, ending up back at the end where it started.
Assembly of this transformer is best done in steps as follows. Please read all the steps before
commencing the assembly:
Step 1 : Carefully unwrap the thick 0.6mm (AWG #22) wire, and straighten it ensuring there are no
kinks.
Step 2 : Pass the wire through both holes, starting at the top left, as shown. This is the first turn of
the 3-turn primary winding.
Step 3 : Now pass the wire through the top hole of the binocular core, back from left to right. This is
the next half-turn of the primary winding, bringing the number of turns so far to 1.5; now we must
make the center tap.
QDX assembly Rev 1.00
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