The AM Forum

It happens many times experimenting that you just need a bit more amplification somewhere. There are many IC nowadays that give you a certain amount of gain at low cost, but very few are adjustable. And, many times you just don't find them in the junk box. But transistors are always there...
So a small circuit attached. The amp has in input impedance set by R1. So for 50 Ohms, use 47 Ohms. The gain is set by R2, actually by R2/R1. So if you take 470 Ohms, you have 10 x voltage gain is 20 dB. Take a 1 k pot and you can adjust the gain. Take R5 zero and you have 0 Ohms output impedance, Take R5 47 Ohms and it is a 50 Ohms output impedance.
R4 should be selected for the current demand at the output. Low power RF amps, 220 Ohms will do fine. and your second transistor will take approx 2 1/2 mA. Take 100 Ohms and your second transistor takes approx 5 mA.
If you need some voltage swing, than you should put in R opt. If R opt is approx R2/2 (half the value of R2), your amp is able to swing approx 3 V tt Without R Opt approx 0,8 V tt
R3 depends upon the type of transistor and the upper frequency limit you need. For general purpose transistors like the BC546, 2.2K will do fine and you amp has a BW of approx 10 MHz Using RF transistors with an Ft of approx 2 GHz and R3 = 1k at  Vcc 12 V, you can expect approx 250 MHz BW
I used this amp to have a little more noise in my noise canceler, In a wide band noise generator wit a zener diode that give 0dBm from 1 to 500 MHz (used for bandfilter adjustment together with a spectrum alalyser of for adjusting bandfilters at max)
and many other projects and experiments. So I thought sharing it

Very Helpful! Thanks!

Here is the amp used for a wide band magnetic loop antenna. R1 is deleted, the loop needs zero ohms load.