Help needed in supplying power to my Low-Noise Amplifier

Hello, I recently bought this LNA to capture signals in the frequency range between 430 and 440 MHz with an antenna. Unfortunately, I have never seen this type of connector to provide 12 V DC, marked with the red rectangle.

The whole configuration is to use a HackRF one that’s is connected to a raspberry via USB and to the LNA using a cable with N-type to SMA plugs. I have an UHF antenna (cross yagi) a polarization switch device (which should be power up by a 12 DC power supply as well). On the raspberry I installed GNU radio to receive and process the signal. So the connection is raspi - hackrf - LNA- polarization switch device - antenna
The question is, do I need to provide power to my LNA separately, or will the HackRF One supply it when connected?

If that’s not the case. Does anyone know how to supply power to the LNA? My plan is to buy a 12 V DC power supply (like pic below) and use a cable soldered to the LNA and a female “jack” connector. Feel free to correct me. Would it also work to solder them to the 12 V DC power supply?

This is a general question: What parameters should I take into account before soldering a power supply? Could anyone give me an example of a DC power supply? I don’t want to ruin the LNA.


Hello… I think you pull the loop in the red square you outlined, it’s like a plug I think… Also you could email them… They’d love to hear from you.

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Hi ED190

The +12v point is just a feed-through the metal box. It is not a connector plug or socket. You will notice a lug on the bottom of the feed-through against the metal case for the Gnd/0v point. I note that the case is not waterproof and for best performance you want this out near your antenna. I have a similar setup.

Basically I mounted the LNA in a nice waterproof box and added N-Type Connectors + tails into and out of the LNA plus a 5-pin waterproof connector for the DC. I then ran a +12v DC feed alongside my feeder from the shack out to the antenna.

In the shack, I actually used an old RPi with a GPIO Controlled Relay and Node-Red to allow me to turn the +12v on and off but you could use a simple switch.

One last point……if you have other transmitters nearby (ie Satellite uplink on 2m) you may well want to add some additional BPF or HPF filters to prevent intermod/interference issues in the SDR……so make your weatherproof box big enough for this.

Hope this helps.

John - VK4JBE

Good morning,
As I see, is a solder connection, not a plug connector. You have to solder the wires.
Few suggestions:

  1. If you want to install outside, on the mast, use a waterproof box and put the LNA inside.
  2. I am not using HackRF, so I can not say more. Most probably, how I see the LNA, you have to use a separate power supply.
  3. Pay attention to the power supply. Dont use cheap transformers for charging different devices, because the voltage is not full rectified. Find a linear power supply, 12 V regulated is the best option (you shall minimized the noise).
    Dont hesitate to ask more details if you need.
    Cristian Moldovanu

Hi! Thank you for the reply and advice! Do you have any suggestions for a good or at least moderately powerful power supply for the LNA? I am kind of noob here.

As I saw in LNA-70 datasheet, you need min. 100 mA / 8-14 V. So, is not necessary a regulated power supply, but my opinion is to find a linear one, not a switching one (let say, 12Vdc - 1 A).
Is hard for me to give you suggestion (I dont know what suppliers you have in your aria), maybe you can find some models and post here . Anyway, is better to have the second opinion from other forum participants.
In my case, I am using an old PS from Yaesu (20A/13,8V, for FT107M and FT920), and I have built a regulated stage with 7805 (for SPF5189Z).

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