HiLetgo 0.1-2000MHz RF WideBand Amplifier 30dB High Gain Low Noise LNA Amplifier

This LNA is a good deal for a good and easy-to-live-with amplifier. It uses a BGA2869 as the main amplifier IC (thanks to another reviewer for the info!). One notable point is that apparently a batch of these were populated and shipped with incorrect values for the resistor that drops voltage from the 9-12V input down to the 5V that the chip requires, so check when you receive it that it has a 220 ohm resistor and has the code 221 (5%) or 2200 (1%) marked on it if you plan to power it from the VIN pad. This problem is apparently so rampant that some other product photos for other listings on Amazon actually have the wrong part visible. Note that there were some earlier revisions that have a different MMIC amp or different layout as well that have reviews included in this listing. Instead of powering it through the VIN pad, this PCB's real party trick is that it can be modified to be driven from a 5V bias T voltage from the receiver that many SRD dongles (like the RTL-SDR v3 and v4) can provide with only a piece of resistor leg or jumper wire, requiring no outside power supply. Just solder a jumper from the center RFout pin on the SMA connector to the node that connects to the Vcc pin on the IC, as seen in the photo. The bias T option can be easily enabled in most SDR software like SRD# or SDR++. The LNA draws around 25mA and the RTL-SDR is rated to source 180mA. I also included screenshots of SDR++ tuned to a weak broadcast FM station using the dipole antenna kit offered with the RTL-SDR v4 so that you can see the gain difference. The only difference between the two screenshots are with the LNA included and removed from the coax line. You can see the difference between the waterfall graphs on the screenshot with the amp removed, and can see the difference on the SNR meter on the top right between the two. Note that both input and output on this amp are female, so you'll need a male-to-male SMA adapter to connect it in-line with this antenna kit. Overall, this is a nice amp for a good price, the PCB is laid out well with good via fencing for RF signal integrity, and has a fair amount of vias to thermally connect the chip to both the top and bottom ground plane for cooling.

This preamp works fine, but I think you have to apply it correctly. It's a GaAs Rf amplifier chip, similar to unit such as the Avago 82563, but not that -- possibly a Chinese clone or variant of a different chip. This one appears to run with a current of about 35 ma to deliver its full gain, and is intended for 5V operation. The sellers have adapted it to run at 9-12 volts by adding the 220 ohm resistor, to drop the voltage down. If the voltage is reduced too much, its gain goes down. In fact, this is a good way to make a variable gain preamp - by driving it with different voltages (without a dropping resistor), say between 3V and 5V. At the lowest voltages, it actually becomes an attenuator. Of course, the current consumption is fairly high for that application -- you might do better in your attenuator circuit by just using a PIN diode. The 220 ohm resistor permits full output when connected to 12V, but at 9V the gain will be much less, which may be why some reviewing it here have had mediocre results with it. If you intend to use it at 9V, you best reduce the resistance. In my application, using two Lithium Ion batteries (3.2-4.2V each) I found a good choice was to change the 220 ohm resistor to 120 ohms. However in my circuit, I also added a 1 mH choke as shown, which has 33 ohms series resistance, so my resistor is actually 100 ohms. The lower the voltage you run it from, the more the inductor is necessary for best output. Check that it is drawing at least 25-35 ma. Also note that it's good to mount the unit in a grounded metal box. Traditionally, the hobbyist mounts these kinds of devices inside an Altoids tin. In my case I used some copper tape lining inside a plastic box. The seller has stripped down their product here to the bare minimum, and I think they could have done a better job making it usable over a wider voltage range. But with care, it will give excellent results. I have two cautions. First, don't try to run this from 5V -- unless you make the modification I suggest (small resistor + RF choke). Second, be careful soldering around this, because GaAs circuits die very easily when treated roughly. If you're not comfortable making changes to the circuit, perhaps it would be better to get one of the other units. Or, get a transistor-based (Jfet) preamp. Those would be more costly, though. Only the very low cost justifies this circuit.

This amplifier is perfect for increasing the reception of an RTL-SDR dongle. It just about covers its entire tuning range, and then some. I've mainly been using it for shortwave where it has dramatically increased the number of channels received. It's also proven itself well on FM (just don't overdrive the SDR frontend!) and other bands. Just one caveat: you'll need to BYOP (Bring Your Own Power) as its DC-blocking capacitors prevent it getting power from the coax. A nine-volt battery should do the trick however. Interestingly enough though, the amplifier ("N02" INA-02186 perhaps?) is designed to take bias-T power on its output pin (7V max), meaning that those adventurous enough to make some slight modifications might just be able to power the amplifier straight from the RTL-SDR! As mentioned before, this amplifier performs quite well and can in fact attain its advertised +30dB gain. However, do note that, like any other LNA, it will amplify the noise floor somewhat as well. In summary, this amplifier is ideal for anyone wanting an inexpensive upgrade for their RTL-SDR.

These little amps worked great a couple years ago, but the new units I recently returned did not work at all. The active component was different than the previous units. Don't know why but no gain at all. So after having installed them, I had to remove and return. Now the latest email says one wasn't returned, even after the return was completed in full on the order page. So a problem there perhaps. Anyway, don't buy these and if you do, test them before going to any effort of installing and counting on them.

Prodotto usato come preamplificatore HF in un ricevitore FT-277 che normalmente non ha di preamplificazione. Segnali passano da 3 a 8 e basso rumore di fondo. Consigliato. Pilotato con alimentazione tramite potenziometro da 500 ohm in serie è possibile variare il livello di amplificazione ma non solo, diminuendo la tensione si ottiene una attenuazione del segnale in ingresso. In pratica variando la tensione si passa in continuità da amplificatore ad attestature. Occhio alla schermatura, è facile ottenere inneschi a motivo dell'elevato fattore di amplificazione. Io l'ho chiuso completamente in una scatoletta di lamierino completamente saldata. Allego toto del montaggio e della scatoletta variatore di tensione.

I've tried a few of these cheap Chinese preamps and most suck, but this one boosts the signal (and noise of course) from both tuned shielded receive loops and untuned loops on topband and 80m, allowing me to phase receive antennas against my main transmit antenna (3/8 wave inverted Ls on those bands) and null out local interference - or to phase receive antennas against each other. Obviously they work better right by the loop. I used a 12v supply with them. The actual noise figure of the amp itself isn't something I can test.

This product does indeed provide ample amplification, however, the lack of shielding on this product can cause awful amounts of noise to be amplified, too. Additionally, it seems part of the LNA's circuit resonates on a frequency in the FM Broadcast band. With or without and antenna, you can hear several local FM stations on top of each other, no matter where you tune, drowning out everything else. If you can find a way to shield the LNA effectively, it may be of better use, however, as is, I cannot recommend the product.

Il mio non funzionava restituito . Alcuni dicono che e' errata la resistenza da 2,2 k, infatti sostituita correttamente con 220 ohm tutto ok

Works well. Using on 137mhz ( Pi SDR server) & 156/7mhz (traditional scanner). I do have an FM band stop filter fitted before the amp. Fast dispatch. Recommend.