Instruction manual

DDF1  27
ANTENNA SYSTEM ASSEMBLY
Roll those sleeves back up; we’ll get to the antenna switcher and individual
antenna assemblies to complete the Doppler DF kit.
Have a look at the ANTINT-1 and ANTMTG-1 circuit boards. Note that these
circuit boards will be operating at RF frequencies and proper assembly tech-
niques (i.e. short component lead lengths, coaxial cable connections, etc.)
will be critical on these boards. To minimize these impedance destroying
lead lengths, we have opted for a “surface
mount” procedure of the components. In-
stead of the typical “thru hole assembly“ you
have completed on the main board, the com-
ponents on boards will be soldered on the
same side of the circuit board. It is therefore
necessary to pre-form the component leads
and trim excess leads prior to the component
being installed. Take a look at the drawing show-
ing how to form the leads for the inductors and diodes. Remember to keep
the body of all components tight to the board to minimize lead length.
1. Form and install the four(4) 1N4148 diodes D1, 2, 3, 4 into their re-
spective positions on the circuit board. Use the shortest lead length pos-
sible. Note that these components are polarized. Install the banded end
as shown in the parts diagram. Don’t worry about too much heat from
your soldering iron, you will not damage the diodes.
2. In the same manner form and install four(4) 1.2uH (brown-red-gold)
inductors L1, 2, 3, and 4. Keep those lead
lengths as short as possible.
3. Install eight(8) .001uF (marked 102),
C1-C8, disc capacitors on the board.
Install these so they lay flat on the
board keeping the leads as short as
possible!
WHIP ANTENNA AND ANTENNA MOUNTING BOARD INSTRUCTIONS
You will need to mount two components as well as an antenna whip to each
ANTMTG board
1. Install a 1N4148 diode on the ANTMTG circuit board in the same
manner in which you did on the switcher, keeping those leads as short
as possible.
2. Install the 1.2 uH inductor in the L1 position.
3. Repeat steps 1 & 2 for the remaining three(3) circuit board assem-
blies.
PAD
SOLDER
FORMED
LEAD
102
CAPACITOR LEAD
FORMING
PAD
SOLDER
FORMED
LEAD
DIODE & INDCUCTOR
LEAD FORMING