High IP3 LNA by PA3BIY

Working seriously DX on 144 MHz requires the use of a low noise preamplifier (LNA). In addition, if you have several meters of coax from your shack up to your antenna system it's recommended to integrate a LNA into your system. For several years I used the preamplifier "SP2000" by SSB Electronics. This preamplifier worked very reliable and without complains. But due to the electrical datas (NF = 0.8 dB / Gain = 20 dB), which are not state of the art anymore, I was looking for a new reliable, more efficient but simple LNA. I found the high IP3 LNA by PA3BIY, which fulfilled all of my requirements.

The technical details are:

  • Gain > 22 dB
  • NF < 0.2 dB

You might also take a look at the schematic of the preamp here and the measuring protocol done by PA3BIY.

In order to use this LNA properly, I had to modify my FT-847 tranceiver. I wanted to have a separate TX and RX line to my mast mounted LNA. I quickly found the nice and simple solution done by Günter, DL4MEA. He has some nice detailed pictures on his web page. If you want to see how I realized the mod, check this high resolution picture here.