I designed a small signal 2m RF amplifier around the transistors that I bought. I didn't want to reuse someone else's entire circuit because I wanted to understand how it works. I maybe 10% understand it now (this is a complex topic!), but that is enough to make something that looks like it should work. Simulated in LTSpice, but I will attempt to build.
Built around the BFR193 which is a really low noise transistor and is like €0.16/ea. #HamRadio #AmateurRadio
If you know more than I do (lots of you do!) please tell me if something there looks dumb, wrong, or sub-optimal. Be nice though, I'm learning :)
It's quite narrow-banded (what I wanted) and delivers about 22db of gain.
Have you seen this reference? https://www.worldradiohistory.com/BOOKSHELF-ARH/Technology/Sams-Books/SAMS-RF-Circuit-Design-Bowick-1982-191024.pdf
This might be worth looking at as well if you have time: https://ia800604.us.archive.org/19/items/SolidStateDesignForTheRadioAmateur1986/Solid-State-Design-for-the-Radio-Amateur-1986_text.pdf
FYSA, here’s a wacky amp I put together from one of those wide-band self-biasing amp “pucks” years ago. Thought it was pretty good for lower frequencies then, but WOW, look at that gain peak up around 500 MHz. An oscillation ready to happen!
#HamRadio#RFFun#AmplifierOrOscillator
I tested the input and output impedances in LTSpice and both are near 50 ohms.
I used the SPICE model from Infineon, found here: https://www.infineon.com/part/BFR193#design-resources
I should mention that that 50 ohm resistor on the output is not part of the circuit, it's there for SPICE sim.
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