Hi I'm doing some research on radio frequency circuits in hopes of playing around with them a little. Whenever, I see a basic RF circuit, especially AM circuits, there are always transistors. Are those for amplification purposes only or is there some other use for them in the network? Could I substitute an amplifier IC for the transistor and its accompanying components? (resistors and capacitors) Thanks.

 

Hi I'm doing some research on radio frequency circuits in hopes of playing around with them a little. Whenever, I see a basic RF circuit, especially AM circuits, there are always transistors. Are those for amplification purposes only or is there some other use for them in the network? Could I substitute an amplifier IC for the transistor and its accompanying components? (resistors and capacitors) Thanks.

depending on the arrangement they are also used for the modulation...

 

Do you know how they are used for that?

 

Do you know how they are used for that?

http://www.reconnsworld.com/transmit/fm_trasm.gif

Here's a FM transmitter circuit...
The first stage modulates the base for the second stage at frequencies above DC(AC coupling)

 

Hi I'm doing some research on radio frequency circuits in hopes of playing around with them a little. Whenever, I see a basic RF circuit, especially AM circuits, there are always transistors. Are those for amplification purposes only or is there some other use for them in the network? Could I substitute an amplifier IC for the transistor and its accompanying components? (resistors and capacitors) Thanks.

I suggest you have a look through the ARRL Handbook or something similar.
Transistors (both BJTs & FETs) are widely used in RF circuits,as are ICs.

The ICs used at RF are often specially designed for such frequencies,& using a standard Op Amp or similar,may yield disappointing results.

Some RF beginners on this forum seem to get hung up on low frequency design & construction methods which don't work well at higher frequencies.
Also,many "example" circuits which appear on the 'Net are merely to illustrate concepts,& do not lend themselves to practical use.

 

Even in a receiver there are transistors that are used as oscillators to provide various useful functions. Learning to read datasheets is the key to understanding what you can and cannot do with a component. A serious study of RF engineering includes the acquisition of a deep understanding of passive AC circuits involving inductors and capacitors. A little algebra of complex numbers never hurts either. You can hold of on the calculus and differential equations for a while, but not forever.