CQ CQ CQ: #HamRadio – International Space Station UPGRADED

Although I am a NASA certified Space Shuttle Door Gunner and a certified expert on the Chemical Oxygen Iodine Laser, I have not yet had a contact with the International Space Station.  Contact, that is, via radio.

I received a Just Too Cool story from a reader.

Via K0LWC comes this:

New Ham Radio Onboard The ISS Is On The Air

The Amateur Radio on the International Space Station (ARISS) team has announced the new ham radio FM repeater is now active aboard the International Space Station (ISS) as of September 2, 2020 at 1:02 GMT.

Ham Radio operators have enjoyed making contact with the ISS for many years. The holy grail has always been talking to ISS astronauts on FM simplex (145.800) — but those can be rare chance encounters. Ham radio operators have also enjoyed slow-scan television (SSTV) broadcasts and APRS packet radio via the ISS digipeater. Now we get to work the world’s most expensive FM repeater thanks to the new InterOperable Radio System (IORS) installed on the ISS.

The InterOperable Radio System (IORS) replaces an ancient Ericsson radio system and packet module that were certified for spaceflight over two decades ago. The 5 watt HT that was aboard the ISS was getting worn out after many years of use. The Ericsson radio looks like something from a 1990s episode of Cops.

5-watt Ericcson radio aboard the International Space Station that has now been replaced by the new InterOperable Radio System (IORS) radio system.

The new IORS was launched from Kennedy Space Center on March 6, 2020 onboard the SpaceX CRS-20 resupply mission. It consists of a custom space-modified Kenwood D710GA transceiver and an ARISS-developed multi-voltage power supply. The equipment was installed by NASA astronaut Chris Cassidy (KF5KDR).

New Kenwood D710G ‘Space Flight Edition’

The radio now being used is a Kenwood D710G and was engineered specifically for space flight. JVCKENWOOD USA and the ARISS worked closely to modify the D710G. The upgrades were performed by JVCKENWOOD and include:

  • Output power is hardware limited to 25 watts for the safety of the International Space Station
  • Custom firmware and menus tailored for operation onboard the ISS.
  • Higher output/high-reliability fan to allow continuous repeater operation.

Continuous fan operation is an important feature in space for the reliability of the radio. There is no convection in microgravity, so all heat-generating components need to be cooled by moving air or conduction. If the radio burns up, there isn’t a Ham Radio Outlet down the street to grab parts.


He goes on to describe the antennas… because it is always all about the antennas.

The ISS features four different vertical antennas on the spacecraft. The reason for four antennas is redundancy in case of an antenna failure. They are made of flexible metal tape that are coated in Kapton, a polyimide film that can withstand extreme temperatures. The antennas are designed to withstand kick loads of 125 lbs.

Three of the four antennas are identical and measure 0.5-meter (1.5 foot) in length and each can support both transmit and receive operations on 2 meters, 70 cm, L-band, and S-band. The fourth antenna has a 2.5-meter (8 foot) long vertical whip that can be used to support High Frequency (HF) operations, particularly on 10 meters. However, no HF radio is currently aboard the space station.


It ain’t ZEDNET but it is pretty cool anyway.


About Fr. John Zuhlsdorf

Fr. Z is the guy who runs this blog. o{]:¬)
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  1. jackhaefner says:

    I remember making my first satellite QSO about 9 years ago: with a lowly HT and sky-pointed handheld Yagi, I could point it at the satelite who would retransmit my signal to another operator about 600 mi away. Just amazing. Makes the line-of-site nature of VHF/UHF transmissions all the more obvious.


  2. It may not be on Zednet right now, but nothing stopping me from ginning up a simplex node tuned to the ISS frequency, linking that via my Allstar cluster which also cross-connects to a DMR/Wires-X bridge in the cloud….and making it available that way to the ZedHeadHams.

    Now you have me thinking, FrZ…

  3. doghouse says:

    Father, I feel the urge to go backwards. When I was first licensed, it was 75-watts with a crystal. Without a license, I now possess the capability of a conference call with Putin, Trump and Bette Midler (and to e-mail you). I kinda want to get licensed again to see what 5-watts cw will do. The sunspot cycle is on the way up, you say? 73.

  4. JonPatrick says:

    @doghouse go for it. Now would be a good time before the FCC raises the license fee. You would need at least a General if you want to do serious HF. Even with the low sunspot cycle there is still plenty of activity on 20, 40 and 80 meters. The other day I heard a chap from New Zealand at my shack in Eastern Maine coming in on 20 like he was next door. 73 de KC1EFW.

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