RJ 2.0 Radio Telescope – Building & Testing

The Radio JOVE 2.0 radio telescope is comprised of a wideband receiver and an antenna that operates over an 8 MHz (MegaHertz) span of shortwave frequencies centered on 20 MHz. The receiver is a commercially-available Software Defined Radio (SDR) from SDRplay (, a UK-based company that manufactures SDR radios. Because this radio does not require construction, no tools are needed. You set up the receiver by simply attaching cables and downloading and installing radio control software.

You will construct the dual dipole antenna, requiring a soldering iron, solder, and basic tools for stripping the wires, installing the connectors, and constructing the antenna support masts. A professionally built antenna is an optional purchase that comes with all connectors installed. Still, basic tools will be needed for constructiong the antenna's support mast. A coaxial transmission line carries the radio signals from the antenna to the receiver. A USB cable carries the radio signals from the SDR to the computer and the display software.

Fabrication of the radio telescope is covered in detail in the receiver and antenna construction manuals. The receiver manual contains assembly instructions including tune up and troubleshooting procedures. If you have difficulties in successfully completing the receiver the Radio JOVE staff are available to help. As a final resort you can send the receiver to a Radio JOVE staff member who will get the unit working for a nominal fee.

The assembly of the radio telescope is covered in detail in the receiver and antenna manuals. These manuals also cover troubleshooting procedures. If you have difficulties in successfully getting the radio telescope working, the Radio JOVE team members are available to help.

Download the Radio Telescope Manuals

Testing the Radio JOVE 2.0 radio telescope

Testing the Receiver and Antenna Together

Before making your first observations it is a good idea to set up the antenna and receiver to confirm that everything is working properly. For this test you can set up either a single dipole or the dual dipole array. Note—do not do any testing of the receiver and antenna if there is nearby lightning.

We recommend two different levels of testing:

  1. Basic Test: Connect the antenna to the receiver and the receiver to the computer to look for an increase in background noise.
  2. Second Test: Test the Receiver using the SDRuno software to check for local broadcast stations and/or AM or FM radio stations.

1. Basic test (Antenna and receiver)

The simplest test is to disconnect and reconnect your antenna while the software is running.

  1. Disconnect your antenna - With the software running (SDRPlay2RSS with yellow Integrate button and RSS software Started) disconnect your antenna from the SDRplay receiver. The spectrograph will go nearly black (see figure below). You might see some small interference at the bottom or top of your chart.
  2. Connect your antenna - you should see a good color spectrogram like the figures below. The figure shows many horizontal bands of interference and a particularly strong one near 18 MHz. Some horizontal banding is normal. By some lucky timing, the first figure also shows a weak solar burst as the near-vertical enhancement in the spectrogram. The second figure shows a 24-hour spectrogram showing the much quieter background during the local nighttime.

With the antenna connected you should see a large increase in signal denoted by the colored background after the antenna is connected. This is the galactic background radiation caused by relativistic electrons spiraling in our galactic magnetic field. You may also see additional signals due to terrestrial sources, typically seen as horizontal bands on the spectrogram. At night you will see a more constant background noise level with fewer stations.

If there is no change in the background when the antenna is connected, check the connections and connectors between the antenna and receiver. If you do not see a significant increase in the background either the software is not set up correctly or the receiver is not working properly.

Example Radio Jove spectrograph output from RSS
Example Radio JOVE spectrograph output using RSS display software. Note the large increase in signal denoted by the colored background after the antenna is connected.
24-hour spectrograph output
Example 24-hour Radio JOVE spectrograph output using RSS display software. Note the clear difference in the nighttime observations on the left and the daytime observations on the right. Local interference is more prevalent during the daytime.

2. Second Test: Receiver test using the SDRuno software

SDRuno is the software that comes with the SDRplay RSP1A receiver. If you have not already done so, follow the download and software setup instructions in the Radio JOVE 2.0 receiver manual.

  1. Start SDRuno — Start this software separately without RSS software — Click on the SDRuno icon on the desktop and multiple windows will open to let you control the radio. See the figures.
  2. Set the Gain, Frequency, and Mode:
    1. Set the Gain to Maximum.
    2. Set the Mode to AM.
    3. Set the Frequency in Hertz (e.g., 1,080,000 Hz in the figures).
    4. Unmute the audio and press "Play". You should see a waterfall spectrum and you may hear the hiss of an untuned radio.
SDRuno Screenshot #1
A screenshot of the SDRplay: SDRuno – The Very Basics video highlighting the key settings to check that your radio is working.
SDRuno Screenshot #2
A screenshot of the SDRplay: SDRuno – The Very Basics video showing the broadcast spectrum at 1080 kHz. This confirms your radio is working properly.

More tutorials and information about the SDRuno software from SDRplay (

  1. SDRuno software download:
  2. SDRplay SDRuno User’s Manual:
  3. SDRuno - The Basics (29:37)
  4. SDRplay: Antennas and Signals for newcomers to SDR receivers (15:46)
  5. All Documentation videos from SDRplay:
examples of assembling RJ2.0 radio telescope

Soldering Techniques

Use only the recommended soldering iron (25-30 watts), preferably temperature regulated with a small tip. Keep a wet sponge near the soldering iron. KEEP YOUR SOLDERING IRON TIP CLEAN! When it gets dirty (black crud on tip), wipe the tip on the sponge.

When you solder, place the iron-tip in contact with the wire /component AND in contact with the printed circuit board (contact both at the same time). Another tip: to get the solder to start flowing after cleaning the tip, quickly melt a drop or two of solder onto the tip (called "tinning the tip") and then immediately apply the tip to the board/wire, heat both up and apply solder to the joint.

When solder flows smoothly and covers the joint remove the iron. The solder joint should be shiny, not gray and dull (a cold solder joint). This process should not take more than 5 seconds from grabbing the iron to putting it back in the holder. If you apply too much heat to the joint, the heat may damage a component.

You might practice soldering on an old PC board (preferably with holes in it). Try soldering scrap pieces of resistor leads to a terminal on the board until the connections look good. That way you can get a feel for how much heat is needed to get a good solder flow in a minimum period of time.

Recapping the soldering procedure:

  • Wipe the tip on the sponge.
  • "Tin" the tip with solder.
  • Apply the tip to both the connector and wire
  • Add solder to the joint (let the solder touch the connector and tip)
  • Let the solder flow for a second or two.
  • Replace soldering iron. The new solder joint should be shiny (not dull).

View this how-to video on soldering: video title