FRB 1 Watt RF Amplifier Kit
Assembley Instructions


      Begin by laying out the parts on the circuit board to get a feel for the situation. Solder the components to the pads and areas indicated in the layout diagram below. Keep coil, resistor, capacitor, and inductor leads as short as possible and raised about 1/16 to 1/8 inches above the surface of the circuit board. The area surrounding the pads is ground. C1 & C2 are soldered at one end to the ground area as well as the shield braid on the coax cables. Slip the top hat heat sink on Q2 for proper heat dissipation.

Q2 and heatsink
      With an input level of 10-15mw, tune variable trip capacitors C1-C4 for maximum power - do not exceed 1 watt. Be sure to have a proper dummy load (50 ohms) or tuned antenna connected to the output, doing otherwise will likely destroy the transmitter.
1 Watt RF Amplifier layout diagram


Parts List

Quantity
Description
Part Number(s)
410-50 pF variable trimmer capacitor (orange or yellow)C1, C2, C3, C4
40.001 mF capacitor (marked 102)C5, C7, C9, C12
3-.1 mF capacitor (marked 104)C6, C8, C10
110 uF electrolytic capacitor (observe correct polarity)C11
14 1/2 turns #18 tinned bus wire, 3/8" dia.L1
16 1/2 turns #18 tinned bus wire, 3/8" dia.L2
2three ferrite beads of #20 bus wireL3, L4
16 turns #26 enamel wire through ferrite beadL5
10.5 uH inductor with ferrite bead on the lead connected to 12 voltsL6
12N4401 or MPS918Q1
12N4427 (note: a 2SC1970 can be substituted for higher power output if proper heat sinking is observed. this transistor can be ordered as an option with the correct heat sink for $8 postage and handling included) Q2
11.5K 1/4 watt resistorR1
120K 1/4 watt resistorR2
1300 resistor with ferrite bead on the lead connected to 12 voltsR3
2SO239 socket
2banana plugs (1 each red and black)
2banana sockets (1 each red and black)
5ferrite beads
4-40 nuts
4-40 bolts
RG174 coaxial cable
hookup wire
soldering lugs