Radio observation in hydrogen line (1420MHz)

Progress on construction of 1420.405MHz Interferometer using AD8302 chip 16/11/2023

See below for current progress on construction:

My interferometer is based on Jan Lustrup’s Simple Digital Interferometer – Schematic below. Jon is a member of SARA (Society of Amateur Radio Astronomers) in USA, and I am very grateful to him for sharing his design with me and encouraging me to have a go at making it for myself:

Cheap solution to RF protection of AD8302 board:

Mounting hardware:

2 thoughts on “Progress on construction of 1420.405MHz Interferometer using AD8302 chip 16/11/2023

  • jan Henning Holmedal lustrup

    You need 2 Sawbirds,+H1 one at each feed (small green triangle seen at each feed horn)….that’s the need for two Bias “T”. Then you also need a 30-40dB RF amp at each AD8302 input to reach the minimun level the detector needs to work… extra narrow band bandpass filter is optinal to do away with any out of band noise if you have those problems at you location. These RF amps and the AD8302 acts as a “receiver”, so no need for a SDR radio!

  • jan Henning Holmedal lustrup

    Tip: In your “Faraday cage” the metal box needs a lid to be RF tight! A open metal box will not do much to stop any RF from entering.!
    Wires going in or out of the box should go through “Feed thru” capacitors, otherwie outside RF noise will just follow the wires into the box! A small RF choke at each “feed thru” also helps stop any RF leaking in.


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