BLX15 150 Watts NoTune FM broadcast (87,5-108MHz) RF-amplifier

BLX15 150 Watts NoTune FM broadcast (87,5-108MHz) RF-amplifier

All component values are drawn on the .comp and .silklayer bitmaps, with the following
exceptions;

1.- the collector 'choke' is constructed of a 220-Ohms 2 Watts carbon composite (i.e. Allen
Bradley or similar) resistor with an air-coil wound around the resistor body.
the air-coil consists of 5 Turns, 10 mm internal diameter, 1.2 mm enamelled copper
wire neatly spaced over the whole resistor body.
the air-coil is then soldered on both ends together with the individual resistor wires.
2.- the FXC1 wideband choke has 1/2 turn and is mounted vertically (a VK200-19/4B wideband
choke has 2.5 turns, so remove i.e. unwind 2 turns from this choke to get the desired
result)
3.- the resisitor mounted at the base of the blx15 is also a 2 Watts carbon composite
resistor with a ferroxcube-bead over one end of the resistor wire (the one wich is
connected to the base of the rf-transistor). The bead is 3 mm diameter and 5 mm in
length.
4.- connect the bottomlayer (groundplane) on several points (through via's) with the
toplayer of the pcb. THIS IS VERY IMPORTANT!

(!) solder the 2 pcs. 150pF capacitors, the 22-Ohms resisitor (with bead) and the ferroxcube
wideband choke (FXC1) as close as possible at the base of the blx15.

Notes

(I) all capacitors (unless otherwise noted) are silver mica types

VCC = Supply voltage 50 Volts at approx. 3.5 Amps.

CuL = magnetwire, enameled copper wire, insulated (rigid) copper wire e.t.c.
(Note: 1 mm equals approx. to #18 A.W.G
1.2 mm equals approx. to #17 A.W.G
0.8 mm equals approx. to #20 A.W.G
0.3 mm equals approx. to #28 A.W.G.)

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