[G0HZU_JMR]

If you do have a go at making the 145MHz amplifier make sure you use the same 2N3904 manufacturer as me. My parts are OnSemi and were bought from Farnell. I don't recommend buying 2N3904 parts from ebay or from small surplus shops if you want to do critical experiments like this. For most general purpose stuff it's OK to use the smaller suppliers for a 2N3904 but you might not be buying a real 2N3904. To get the same results as me you need a genuine OnSemi part.

The 2N3904 is quite an old part and it is different to other jellybean BJTs even though the datasheet description and specifications appear very similar to other jellybean transistors. The internal die is (was?) made with a very different process (process 23?) and this gives it superior RF properties to process 4 transistors like the BC107, BC547 etc.

See below for an old spectrum analyser plot of a 2N3904 configured as a 1GHz oscillator. I don't think this could be achieved with the BC107 type of jellybean BJT. I suspect I could get closer to an oscillation at 1200MHz with the 2N3904 if I tried again.