ILER-20 MK2 SSB QRP Transceiver Kit
Page 25
Jumpers "E-C-x-y", positioning of the Q14 and D7
The combination of jumpers “E-x-C-y” allows the use of different
types of transistors for Q14. If need be, we can use substitutes with
different lead configurations.
The ILER-20 kit uses a 2SC1969 or 2SC2078 for Q14 and
the
following the jumpers SHOULD BE INSTALLED: “E-y” and “C-
x”.
Cut small pieces of wire to make the connections "E" to "y" and “C” to
“x”.
Make sure that the wires do not touch each other.
The case of Q14 (2SC1969) should be electrically isolated from the
heatsink. Use the plastic washer and the mica sheet provided with the
transistor. Fasten it with the 10mm screw, nut and M3 washer. After
mounting the transistor to the heatsink, verify with a multimeter that the
transistor case does not make contact with the screw or with the heatsink.
It is also recommended to apply a dab of thermal grease on both sides of
the mica sheet.
Install diode D7 with it touching Q14 and the heatsink so that there is heat transfer among them
.
The cathode (marked with a white band on the diode) connects to the pin marked with a GND
symbol on the circuit board.
This diode helps to stabilize the idle current BIAS as the transistor heats
up. Pay attention to the following photo to see how the transistor and diode are mounted.
You may drill another hole on the heatsink if that better suits its position in your box. You may also
mount the circuit board on the rear part of the box with the heatsink external to the box.
DO NOT operate the transceiver without mounting Q14 to the heatsink.
