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150Watt FM Linear

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leosedf

New Member
Hello! here's a 150W Linear for the FM Band. This Linear Amplifier is used by ELENOS. ELENOS Uses multiple of them with splitters and combiners to create power amplifiers with higher output (500-1500W). The power supply is 28V 8Amps. I don't have the PCB layout for now, i hope i'll find it soon.
Thank's





 

jem

Member
Hi:

I fail to see how this circuit can properly work. I am assuming that there is a connection between R5, and C4, C5, and L2; also, I am assuming a connection between R1, R2, R6 and R3 and the gate of Q1.

My issues are:

1. R5 seems to be a very high value to supply any kind of power to the drain of the FET.

2. The values of R1, R2, R6, and R3 would probably turn the MOSFET into a hard ON state. Typically, they should supply just enough bias to overcome the Vth of the MOSFET.

3. I am assuming that you are using the term "Linear" as some RF people use to mean a power amp. The circuit should be operating in class C (or, at most, in class B), which is quite OK for FM.

Thanks,

Jem
 

Nigel Goodwin

Super Moderator
Most Helpful Member
jem said:
1. R5 seems to be a very high value to supply any kind of power to the drain of the FET.

2. The values of R1, R2, R6, and R3 would probably turn the MOSFET into a hard ON state. Typically, they should supply just enough bias to overcome the Vth of the MOSFET.
I think your concerns are because he's drawn the circuit incorrectly, the power input should be at the top of the 15K resistor R5, not at the bottom.
 
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