Hello so attached is my power amplifier that suppose to prove 10 watts into a dummy load using a frequency of 13.56MHz. THE PROBLEM IS THAT IM ONLY GETTING 3 WATTS ON A WATT METER. Im driving 26.4dbm(little over 1/4 watt) into the base of my transistor. The transistor im using is the 2SC1969 BJT. Attached is the data sheet. I use a PI network to match 50 ohm to 5.6 ohm at the base. The PI NETWORK formula is as followed.
Q =√(1/2−1)
Xc1 = 1/
Xc2 = R2 √((1/2)/(^2+1 −1/2))
XL = R1[(+2/2)/(^2+1)].
Then for 10watts of power a load resistance of 7.2 ohm is presented at the collector using the following formula.
Load Resistance = Vcc²/2*Pout
I then use a LCC network to match the 7.2 to the 50 ohm dummy load using the following formula.
XL = QRs
XC2 = RL√[Rs (Q2 + 1)/RL – 1]
XC1 = Rs (Q2 + 1)/Q[QRL/(QRL – XC2)]
L= XL/2πf ,C = 1/2πfXC.
Note i could of just used another PI network here)
The Q have have chosen for both networks is 3.
I cant seem to understand why im only getting 3 watts on the watt meter unless the watt meter isn't calibrated right cause i feel all my calculations and values are correct.
Q =√(1/2−1)
Xc1 = 1/
Xc2 = R2 √((1/2)/(^2+1 −1/2))
XL = R1[(+2/2)/(^2+1)].
Then for 10watts of power a load resistance of 7.2 ohm is presented at the collector using the following formula.
Load Resistance = Vcc²/2*Pout
I then use a LCC network to match the 7.2 to the 50 ohm dummy load using the following formula.
XL = QRs
XC2 = RL√[Rs (Q2 + 1)/RL – 1]
XC1 = Rs (Q2 + 1)/Q[QRL/(QRL – XC2)]
L= XL/2πf ,C = 1/2πfXC.
Note i could of just used another PI network here)
The Q have have chosen for both networks is 3.
I cant seem to understand why im only getting 3 watts on the watt meter unless the watt meter isn't calibrated right cause i feel all my calculations and values are correct.
Attachments

146.2 KB Views: 40

11.2 KB Views: 53