Ramsey Electronics FX Series Manual page 118

IMPORTANT:
DO NOT install any parts near Q8 until after Q8 has been installed in accord
with the explicit directions in Step TX2. If you fail to observe this caution, it
will be virtually impossible to perform the installation of Q8 correctly.
DO NOT INSTALL L9, R32 or L10 UNTIL AFTER ALIGNMENT HAS BEEN
COMPLETED.
C75 is a SMT (surface-mount-technology) "chip" capacitor and is the only
part installed on the SOLDER SIDE (bottom) of the board.
TX1. Install Q9, RF NPN type 2N3866. Let it rest flush on the round
bare area of the board. The holes match the pins, so the tab will point
exactly as illustrated.
TX2a. RF Final transistor Q8 (MRF237 or SD1127) is also installed
completely flush on the board, with the tab oriented toward L9. The case
of Q8 is common to the emitter. Be sure the case stays completely flat
against the top ground plane when soldering the 3 points.
READ CAREFULLY: The following procedure lets the top groundplane serve
as the heatsink for the RF final output transistor. Do not be hesitant in
making a smooth solder bond between Q8's case and the board. An ordinary
soldering pencil tip applied to both the case and the groundplane at the
same time will NOT damage Q8. On the other hand, the lack of a good
heatsink bond WILL destroy Q8 when transmitting. This procedure is
INTENDED by the manufacturer.
TX2b. Now, using only your regular soldering pen and NOT a soldering
"gun," solder the rim of Q8 directly to the top ground plane, starting at
the square tab. Use enough solder for thorough bonding.
A. TX3 Prepare the following tools for installing SMT chip capacitor C75:
•
Tweezers
•
Magnifier (if
needed)
•
Low wattage,
clean soldering
tip.
B. Unpack and study the
design of the chip,
noting both ends are
metallic.
C. Lightly pre-tin both PC
board points.
D. Holding C75 in place across the two tinned points with tweezers, gently
touch one junction with the soldering tip. The connection should solder
Location of C75
C75