MOSFET Linear Amplifier 300W/50MHz

This MOSFET Linear Amplifier has capability to deliver up to 300W for 50MHz. The circuit built based the couple of MOSFET ARF448A and ARF448B.

Circuit Design:

Parts List:
C1 : 215-790pF Arco8 #469 mica compression trimmer
C2,6,7 : 1000pF 500V NPO chip cap, KD9 2020N102J501P
C3 : 20-180pF Arco #453 mica compression trimmer
C4-5,8-9 : .01uF 500V chip
C10 : 1uF/35V electrolytic
D1 : 6.8V 1W Zener diode
L1-2 : ~70 nH, 3t #18 enam. .31″ dia. .25″L
L3 : 2t #20 on Fair-Rite Prod. #2643006302 bead mi = 850
Q1 : ARF448A
Q2 : ARF448B
R3 : 10K NTC Fenwal10 #140-103LAG-RB1
R6 : 1K .5W ten turn trimmer
T1 Pri: 2t #20 PTFE, Sec: 3/16″ brass tube on Fair-Rite #2843010402 balun core
T2 : 6t bifilar #20 PTFE on Amidon #T-94-2 toroid mi = 10
T3 : 3t RG-316 coax, 3t #20 PTFE on three Fair-Rite #5961001801 toroids mi = 125
TL1-2 30W printed line .6″L

It will be the very first recognized class AB application in the ARF448 components. Till now the only other linear application is inside a pulsed-mode linear amplifier for magnetic resonance imaging. The SSB overall performance was encouraging given that these devices have been created to serve the ISM plasma generation marketplace and no interest to linear efficiency was offered in their product. The IMD overall performance with 200mA of quiescent bias was much better than anticipated. The amplifier was tested with as much as .5A of Idq. Whilst the IMD efficiency improves somewhat, the efficiency degrades significantly

PCB Layout:

Component Placement:

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