The Nooelec 50 kHz - 150 MHz 20-dB LNA

I ordered it because the Fobos SDR I was using had pretty mediocre sensitivity, and I wanted to see if a preamp could increase it a bit. The Fobos had other issues too, so I ended up returning it. But I think the Nooelec will come in handy when FM season kicks off next May.

At KONG HQ, we’re no strangers to preamps. We need to split each of our signals to three users using MiniCircuits 8-port passive splitters. Sometimes, the MW band signals are so weak that preamplification actually makes a difference.

However, many DX-ers deal with high noise floors where a preamp won’t help and might even overload the receiver. So, it’s a bit of a mixed bag.

Anyway, I was curious to see how it performs on the SW bands.

This device is tiny compared to what we’re used to, like this 16-dB preamp from DX-Engineering!

Nooelec LNA vs. DX-Engineering RPA-2

So, it’s got SMA ports on both the input and output. You power it with a 5VDC supply through a Micro-USB port. Honestly, it might be a good idea to switch to the more common USB-C port soon.

For this quick test, I set up a Perseus22 with a center frequency of 15 MHz, which lets me receive from 14.2 to 15.8 MHz. I picked 15290 kHz kind of by chance - NHK World Radio was broadcasting in Japanese from the Issoudur transmitter in France at that time. I used a 5-meter high, 20-meter long sloping L-antenna, which worked great. The LNA was powered by a battery bank

So, this is what the spectrum and waterfall looked like before I hooked up the LNA.

The noise floor is around -120 dBm, with signal levels hitting just at or below -70 dBm. When I turned on the LNA, here’s what happened

The noise floor has gone up to about -100 dBm, and the peak signal levels are just below -50 dBm, which matches the 2.5 dB loss the manufacturer mentioned. The 27-dB gain increase on 15290 is because of random and quick signal level changes. We do see a few more signals on the waterfall that might be clearer with the LNA, but there’s also more noise. So, in this test, the LNA likely didn’t help with signal recovery. With a lower noise floor, it might make a difference.

I spent about  USD 35 on the device and another $12 for the slow USPS shipping. Right now, the RPA-2 HF Preamplifier from DX-Engineering (shown above) is priced at USD 270. It’s definitely more versatile. But it makes you wonder: Could we do with less?