Instruction manual

VLF1 • 10
ASSEMBLY INSTRUCTIONS
Once you’ve begun to install some of the longer leaded parts, save a couple
of clipped off leads to use as jumpers in construction of your VLF1 kit.
 1. Install jacks J1, J2, and J3, the antenna input and RF output Jacks.
They are RCA PC mount type. These connectors will “snap” into place
before soldering. Don’t be afraid to completely solder all three ground
connections as these will also limit the “stress” on the input and antenna
connections. Solder all four “tabs” on the bottom. Be sure to use enough
heat to properly “flow” the connection.
 2. In the same manner, install power jack J4.
 3. Install pushbutton switch S1. Orient the switch so that the end of the
switch extends over the edge of the PC board. Be sure to push the
switch flush to the circuit board. Solder all six pins.
That wasn’t so bad, now was it! Recheck your connections for a shiny,
smooth solder fillet connecting the component to the PC trace. Touch up any
poor looking connections. We’ll continue now by building the low-pass filter.
The next few parts will make up the low-pass filter at the antenna input of the
VLF1.
 5. Install C1, .0082µF capacitor (marked 822), by the RCA jacks.
 6. Install L1, 22uH inductor (red-red-black. One of the smaller blue green
or light tan parts that looks like a resistor). You can check with an
ohmmeter to make sure it isn’t a resistor. The inductors have nearly zero
resistance.
 7. Install C2 .015uF capacitor (little brown chicklet marked 153), next to
L1.
 8. Install C3, the other .015uF capacitor kitty corner to C2.
 9. Install L2, 27uH inductor (red-purple-black).
 10. Install L3, the other 22uh inductor, kitty corner to L3.
 11. Install C4, the other .0082uF capacitor.
You have now completed the low-pass filter!
It is now time to wire up T1, the three winding transformer. Don’t be alarmed,
it isn’t that hard. Don’t be afraid to be a bit sloppy with the wire. The ferrite
core is almost an ideal material for wire stripping and if you tug on the wire
and it scrapes against the core, the insulation will come off. This will cause a
short and you will have to rewind the transformer. The wire must be
delicately threaded through the holes in the core.