3
Assembly
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A fine-point, temperature-controlled soldering iron (700-800 degrees F) is required to assemble
this kit. A high-wattage iron or one with a wide tip may damage components, pads, or traces. Use a
minimum amount of solder to avoid ground shorts.
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All parts are installed on the top side of the board except as noted (the side with the relays, toroids,
and microcontroller U1). Double-check all values before soldering, since removing parts from double-sided
PC boards can be difficult.
Place relays at locations K1-K7 as shown by their component outlines. Do not solder yet.
Do not
bend the relay leads.
Using a flat object to hold K1-K7 in place, flip the board over. Solder just one inner pin on each relay.
Inspect the relays closely to make sure that they’re seated flat against the PC board. If not, re-heat the
soldered pin while pressing down on the relay. Once all relays are properly seated, solder all pins.
Trim the relay leads as short as possible to provide clearance for folded capacitors in a later step.
Install the IC socket at U1. Align the socket's notched end with the notch in the component outline.
On the bottom side, install R3 (200 ohms, red-black-brown) and R4 (3.3 k, orange-orange-red).
Install D1 and D2, with the banded end of each diode oriented as shown on the board.
Install ceramic resonator Z1, which looks like a capacitor with three leads. It can be installed in either
of two orientations. Keep soldering time to 2-3 seconds per lead to avoid overheating the part, which can
alter its frequency. Trim the leads after soldering.
Install trimmers R1 and R2 on the bottom side. Make sure they are seated flat against the PC board.
Install RF choke RFC1 (brown-green-black). The leads are fragile—handle carefully.
Install the trimmer capacitor, C9, on the bottom side. The flat side should be oriented as shown by the
component outline, and the trimmer must be seated flat against the board.
Install the capacitors listed below on the bottom side of the board, but don't solder them yet. Leave the
leads about 0.1" long so the capacitors can be folded down in the next step. All possible value markings are
shown in parentheses.
__ C1, 20 or 22 pF (20, 22, 200, or 220)
__ C2, 39 pF (39 or 390)
__C3, 82 pF (82 or 820)
__ C10, 100 pF (101)
