50 Watts FM broadcast (87,5-108MHz) RF-amplifier


Resistors
(values in Ohms unless otherwise noted)

R1 = 100 (0,5W)
R2 = 100 (0,5W)


Capacitors

C1,C4 = 65pF trimmer capacitor, yellow (Philips)
C2,C9,C15,C16,C20,C21 = 10pF
C3,C19 = 33pF
C5,C6,C7,C8 = 100pF
C10 = 470pF
C11 = 100nF/100volts
C12 = 47uF/25volts
C13,C14 = 1nF
C22,C23,C24 = 10pF
C17,C18 = 65pF trimmer (Arco)


Semiconductors

T1 = BLW60 or BLW60(C)


Coils

L1 = 1 turn, 10 mm diameter, 1,5 mm CuAg
L2 = 7 turns, 3 mm diameter, 0,5 mm CuL (closewound)
L3 = 4 turns, 8 mm diameter, 1 mm CuAg (1 mm wire spacing)
L4 = 4 turns, 7 mm diameter, 1 mm CuAg (1 mm wire spacing)
L5 = 4 turns, 9 mm diameter, 1 mm CuAg (1 mm wire spacing)
RFC = VK200 choke


Notes

CuAg = silver plated copper wire
CuL = magnetwire, enameled copper wire
(Note: 1 mm CuL equals approx. to AWG18
         0,3 mm equals approx. to AWG28)

(I)   all diameters are measured from the inside of the coils
(II)  make sure to mount the rf-transistor on a appropriate heatsink and use some thermal
      heatsink compound between the stud of the rf-transistor and the heatsink!
      (Thermal resistance heatsink at least 6°C/W.)
(III) all parts are soldered directly on the toplayer of the pcb.

(C)2005 Helix Inc. The Netherlands.

