Receiver - Antenna Preamp, simple and effective

[@robertsumption1243]

Thanks Bob this is another Bob N8RS Nice simple RF preamp ... I plan to try it on a LOG "Loop on ground " experiment to receive 80 meter Amateur radio hopefully with less neighborhood noise pick up 73.

[@bundylovess]

Nice job big thumbs up

[@blacksmock445]

I didn't catch the type of transistor used. 2N3904, 2N2222 suitable?

[@blacksmock445]

This circuit appears similar to a Cable TV amp circuit I have seen which used 2GHz transistors. I'm sure you used some more common types.

[@n1kpr]

@@blacksmock445 That particular one has 2N3904 devices. There are other quieter devices, but since it's intended use is for MF and LOWFER bands, I left it that way. I cannot measure any added noise in those bands. Yes, the basic circuit is used frequently in TV amps. It is not unique and, in fact, quite common. The reason is that it's simple and effective, has good dynamic range. Of course, the biasing resistors should be selected for best performance for the application.

[@steveratzlaff]

Where does the pot go? Your drawing doesn't show a pot in it.

[@n1kpr]

Hi Steve. Sorry I missed your question. The pots are at the input and output. Input pot has the wiper to the circuit input and the output pot has the wiper to the output connector. That way, the source (antenna) sees a constant 500 Ohm load which should not load-down the source (like a constant voltage source) for almost any antenna. If using an e-field probe type antenna, then you could go to 5K ohms. The output pot has the full 500 ohms across the emitter follower output with the wiper going to the radio.