You can buy PSA4-5043+ receive LNA chips in as little as 20 quantity from Mini-Circuits. They cost around $2.50 each at that quantity. Which is a great deal because they also have built in basic ESD protection. And the quality of the LNA they make its quite decent. Typically the NF is around 0.6 or 0.7 db. Which is low enough to use them for satellite reception. No, they wont cause problems with your receiver, usually, but lets face it, RTL dongles are not the most selective receivers out there. So attenuation is very useful with them. As is a preselector.
In building an LNA the most important things are impedance matching and especially proper grounding. (right underneath the chip) If you use the PSA4-5043+ keep in mind that the current draw is always around the same. around 53ma. Any more than a small bit lower or higher and something is definitely wrong. You should also be able to see any problems with self-oscillation immediately it will show in the current draw as a larger random variation in the current draw than usual. Also it will show up in the rtlsdr's not working properly and possibly producing noise that can be picked up in an rtlsdr or other receiver nearby. All of my recommendations here need to be followed to ensure its not acting up. Yes, you can add filters to roll off unwanted inputs (thats preferable to output filtration)
You can buy an LNA4ALL directly from Adam, by mail. His address is on his web site. $25 is a good buy from a very nice and smart RF designer who deserves your business. Here I am giving you a good idea of whats required to make your own.
If you look for an LNA dev board on ebay you can find PCBs suitable for use with the Mini Circuits devices. You can also make your own and if you have it professionally done, many difficulties can be done for you by the PCB firm.. Its a PITA making PCBs that perform well over this wide range. When I was just starting out I carved one with an x-acto knife. it did not perform well. i used my hand drill (I did not have an electric drill) to laboriously drill holes and fill them with wire for vias. (Its not easy to make vias that way, you have to drill holes and fill them with 1mm wire and then solder both sides to link them, and then chop off the extra right at the surface) Don't skimp on the vias! (or it will self-oscillate) Put them right under the ground pins. literally.
You could also dead bug them. That will work up to around 500 MHz. Its not rocket science. The usual LNA chips you should use are microscopically tiny. They are receive amps, not transmit amps. Big difference! Lots of devices have a similar form factor, so can use a similar pattern.
Proper Grounding of the MMIC and input-output stage isolation and impedance are the most important things. Use a length of good coax of the right impedance on your inputs and outputs and that will make a good design perform at its best. Also pay attention to the DC blocking input capacitor's self resonance and the same with DC isolating inductor . Read up on bias-tees and design so the self resonances are damped. . thats the same set of issues.
A flat copper sheet has lower inductance than most wires. So if you dead bug it then the two legs must connect directly to your ground plane Then use coax (short) for the output and a DC block right there . Use SMD caps (0402 is good) and connect the input directly to the input pin through a capacitor thats literally soldered to the center pin of the input RF connector. So as short as it could possibly be. Leading the RF right into the MMIC's input pin. You can dead bug it but use SMD parts. Just as is, connect them directly to each other with minimal wires. UGLY construction this is called and they are ugly. But it works well. Its a fun project especially when your final result is an LNA that dramatically improves some very weak signal.
Have fun!
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