Simple 15W linear on KV

The described power amplifier is suitable as a supplement to the all-band QRPP TCVR-u with a power of 1W and less. In the bands 160 to 10m, it transmits approximately 10 to 15W. The construction is simple and undemanding, it does not hide any intricacies.

The PA is equipped with a 2SC1969 transistor (Uce = 13.8V, Ic = 6A, Ptot = 35W, G = 11.5dB at 30 MHz, Ft = 90 MHz, Pout = 16W), which is cheap and available. It is of course possible to use another similar transistor.

Excitation is supplied through the input transformer TR1. The quiescent current circuit consists of R1, D1, C1 and C2. Resistor R1 sets the quiescent current to 75mA. Diode D1 should have thermal contact with the transistor case, which must be mounted on a heatsink. The stability of the connection is improved by the negative feedback of R2C3. Due to the wide range of transmitted frequencies, two chokes are used. The output transformer TR2 is wound on a pair of glued toroids made of material T50-61.

The setting of the amplifier is limited to the quiescent current setting. To begin with, we choose R1 of a significantly larger value (2.2k, etc.), which we then slowly decrease until we reach a quiescent current of 75mA.

R1	approx. 470 *
R2	100 0.5W
R3	22
R4	2.2k 1W
C1	100nF
C2	22uF/6V
C3	47nF
C4	100nF
C5	22uF/16V tantalum
C6	47nF
D1	1N4001 and so on.
T	2SC1969
TL1	8uH 35z toroid T68-2
TL2	4z on ferrite pearls
TR1	30/8 from toroid T50-61
TR2	8/20z two T50-61 toroids