August 1986

13

Philips Semiconductors

Product specification

HF/VHF power transistor

BLW78

R.F. performance in s.s.b. class-AB operation (linear power amplifier)

Note

1. Stated intermodulation distortion figures are referred to the according level of either of the equal amplified tones.

Relative to the according peak envelope powers these figures should be increased by 6 dB.

List of components:

OUTPUT POWER

W

dB

%

A

dB

dB

mA

100 (P.E.P.)

typ. 19

typ. 42

typ. 4,3

typ.

−30

typ.

−37

50

C1 = C11 = 150 pF air dielectric trimmer (single insulated rotor type)

C2 = 27 pF ceramic capacitor (500 V)

C3 = C12 = 150 pF air dielectric trimmer (single non-insulated rotor type)

C4 = 180 pF ceramic capacitor (500 V)

C5 = C8 = 3,9 nF ceramic capacitor

C6 = 150

µF/6 V solid tantalum capacitor

C7 = 150 pF ceramic capacitor (500 V)

C9 = 100 nF polyester capacitor

C10 = 750 pF mica dielectric trimmer (single insulated rotor type)

C13 = 750 pF mica dielectric trimmer (single non-insulated rotor type)

L1 = 3 turns enamelled Cu wire (1,0 mm); int. dia. 12 mm; length 12 mm

L2 = Ferroxcube wide-band h.f. choke, grade 3B (cat. no. 4312 020 36640)

L3 = 3 turns enamelled Cu wire (2,0 mm); int. dia. 12 mm; length 12 mm

L4 = 2 turns enamelled Cu wire (2,0 mm); int. dia. 12 mm; length 8 mm

R1 = 27

Ω (± 10%) carbon resistor (0,5 W)

R2 = 4,7

Ω (± 10%) carbon resistor (0,5 W)

Fig.17 Test circuit; s.s.b. class-AB; f = 28 MHz.

handbook, full pagewidth

50

Ω

MGP558

50

Ω

C9

R2

C6

C5

C8

L2

L1

R1

L3

T.U.T.

L4

C11

C13

C12

temperature

compensated bias

(Ri < 0.1 Ω)

C10

C2

C1

C4

C7

C3

+VCC