Electronic – Impedance matching for amplifier output

amplifierimpedancematchingtransformer

I needed some basic advice about impedance matching. I have an RF amplifier with 50 ohm output impedance, capable of generating 400W output power at 500kHz. I am trying to deliver this to a 12 ohm load.

I looked online and figured out that I need to match the impedance of the amplifier to the load. What is the best way to achieve this? Would it be possible to simply use a capacitor and inductor and put an L section to the output of the amplifier? I saw that online stores have very cheap capacitor and inductors that are rated for very high voltages.

If that is not going to work, is it possible to buy any transformers that would do that? For instance I saw that there are many cheap 220V-110V voltage converters, which should have 2:1 coil ratio. So in theory that should convert 50 ohm to 12.5 ohm and matches to my load. Will these work at 500 kHz as required for my application? Or are there other type of transformers that I can use for this purpose (there are many many types of transformers and I got confused which ones are suitable for impedance matching)?

Best Answer

Yes, you can use an L-C network to match your load. It will be very frequency-specific, but as long as you're operating at a fixed freqeuncy, that shouldn't matter too much. But it does mean that it will need to be "tuned" for your application.

A 2:1 transformer would be a more broadband solution, but you definitely cannot use a power transformer designed for 50/60 Hz power, which has a laminated iron core that would be far too lossy at 500 kHz. A large toriodal ferrite core would be much more appropriate.

It might be more appropriate to ask this on Amateur Radio.SE — some hams work at these frequency and power ranges.