Obituary: SUNSAT OSCAR-35

I am saddened by the news that SO-35 appears to be no longer operational. At the time of writing this, the last contact that the SUNSAT team had with SO-35 was on January 19, 2001. Since then, there have been two weeks of unsuccessful recovery attempts. The official press release, dated February 1, 2001 appears here. What follows is personal reflections of the last 16-17 months of my experiences on SO-35.

I first encountered SO-35 in September 1999, after an article about the satellite appeared in APC News, the local amateur radio news service (which I have since become involved with in a majow way also!). The text of the news item as read on air, dated September 8, 1999:

Sunsat over Australia

You may have heard about Sunsat - a South African amateur satellite. Sunsat contains a two metre/seventy centimetre crossband FM voice repeater. The uplink frequency is 145.950 megahertz. The downlink is 436.250 megahertz. Thanks to a doppler correction circuit in the satellite, you do not need to vary the uplink frequency, as with other amateur satellites. However, doppler on the UHF downlink could be as much as plus or minus 9 kilohertz. It is planned that the satellite will be accessible to Australian amateurs this weekend.

Try the following times (in UTC):

: Saturday 11 September

: 02:59 to 03:15

: Sunday 12 September

: 02:20 to 02:38


These times are a goal - software bugs and other difficulties may cause times to differ from those mentioned above.

:The passes over Australia will often enable comms over most of Australia, and then the islands North of Australia including Japan. Communications between Japan and Australia should be possible for a short period.

Please send your comments and experience to


The item above caught my eye, and the following weekend, I gave SO-35 a go. On the Saturday, I was unsuccessful, due to a last minute change of frequencies (from Mode J as described, to Mode B), but on Sunday 12, 1999, I worked a station from a pair of handhelds in the back yard, with excellent signals both ways. I was hooked! :-) APC News again picks up the story the following Wednesday, September 15, 1999:

VK3s make contacts through Sunsat

Last week we mentioned the South African Sunsat satellite that was to be active this weekend. Well, the satellite was active, but it used a 70 centimetres uplink and two metres downlink. This was the reverse of the information publicised before the pass. However, a number of VK3s found out about this before the Sunday afternoon pass.

One of those who made contact on Sunday was Tony VK3JED. Tony worked several stations were heard, including several VK3's, VK2's, VK5's, VK4's and ZL's, some of which Tony was able to work.

All contacts were achieved from a 4.5 watt handheld with half-wave portable antenna. Another handheld was used with a quarter wave whip on received. Signals were extremely strong. Tony's next Sunsat experiment will be to work the bird from a train or tram.

SO-35's signal had to be heard to believed, as many amateurs will attest to. The 2 metre downlink was so strong that I was inspired to attempt to communicate via SO-35 from a tram or train, combining satellites with one of my other interests in radio - communication while commuting. After several attempts at tram mobile operation, success was achieved on the pass of October 2, 1999, when two stations were worked from a tram. The following Sunday, October 10, 1999, saw the first amateur satellite QSO from a train. From APC News, October 6, 1999.

World's first tram mobile Sunsat contact

In news just to hand is word that Tony VK3JED finally succeeded in working the Sunsat satellite from a moving tram on Saturday October 2. Stations worked included VK3WWW and VK3NM. Tony has a recording of other stations who called but didn't make contact - RF noise from the tram meant that reception was not always ideal.

SWLs wishing to send reception reports should QSL VK3JED direct, QTHR in the current callbook.

You can also email if you don't have access to a callbook, to obtain the QSL information. Audio recordings of the full pass and the first QSO with Jack can be found at

The QSO itself can be heard here. The superb audio quality is a tribute to the performance of SO-35's Mode B transponder.

During the following weeks, SO-35 became very popular among amateurs in Australia and New Zealand. Many contacts were had, and a lot of people were amazed at the performance of the satellite. Other amateurs also pushed the transponder to the limit of its performance, including Peter, VK3YE who was the first to work it from a bus. From APC News, Novermber 24 1999:

Sunsat worked from bus

Two MDRC members participated in what we believe to be another world first for contacts through the South African Sunsat satellite. Chris VK3JEG worked Peter VK3YE who was mobile in a bus at the time shortly after noon last Saturday. Peter went on to work one more VK3 and two VK2s from the bus before the satellite pass finished. Equipment used from the bus was a Yaesu FT-290R and quarter wave whip for the receiver, and a Yaesu VX-5R with half wave whip for the transmitter.

An attempt to work train mobile to bus mobile was not successful. Though VK3YE heard Tony VK3JED train mobile at North Melbourne, contact was not achieved. However, several other tests, not using the satellite, were done with Tony - more on this later.

Here's the audio from Peter's QSOs. Again, SO-35's transponder handled the difficult conditions with ease.

SO-35 appeared before the Melbourne's public for the first time on November 6, 1999. From a makeshift portable station outside the St Kilda Hobby Show, more than a dozen members of the public heard contacts with amateurs from Australia and New Zealand. The interest sparked by this exercise led to many questions from the public and some discussion of satellite operation.

I first became closely involved with the SUNSAT team around the start of 2000. At that time, there were some difficulties with updating the website, due to the Christmas holidays, and time zone differences were making things more difficult. As a result, I started receiving information direct from the SUNSAT team, and began publishing a series of pass predictions for Australia and New Zealand. I had been doing this since late 1999, but increasing demand from amateurs from more regions meant presenting data for several major regional centres and publishing those predictions on a weekly basis. This proved popular among local amateurs. This new colour coded tabular format began on January 15, 2000 and continued until just before SO-35 failed.

On February 26, 2000, SO-35 strutted itself in front of Melbourne's public for the second time. This time, a dedicated satellite station was setup at the St Kilda Hobby Show, with an FT-847 and some Yagis outside. Many people were treated to strong signals from all over Australia as SO-35 passed northwards over central Australia.

March 2000 saw two firsts. Firstly, an unexpected parrot mode on March 10 caused a little bit of confusion, but once that settled, a few stations were worked successfully. Secondly, on March 14, 2000, SO-35 became available on weeknights for the first time. Now, we had the satellite for 6 days per week, meaning many more opportunities to work the bird.

I'll never forget the 31st of March 2000. I was at a social gathering of local amateurs, when a pass came up. I had promised to demonstrate SO-35 to them, and at the appropriate time, we gathered in the car park of the pub (after a few drinks and a lot of food! :) ). While I was busily working the bird, one of the foxhunting guys grabbed a snigger out of his car and proceeded to track the satellite as it moved across the sky (We don't know how he was going to claim finding that 'fox'! :) ), while I convinced another operator to try for a contact with 500mW from his VX-1R (he was successful, BTW!). Again, SO-35 left a lasting impression on many people.

The following week, on April 5, I was intervied by a local radio station on my involvement with amateur satellites. SO-35 featured well, with several audio tracks taken from various passes being featured during the interview.

April 2000 was also when I took over scheduling the voice transponder for Australia and New Zealand. Up until then, all scheduling had been done out of South Africa, though I occasionally added advisory input. From April, VK/ZL schedules were prepared by me and then emailed to the SUNSAT team for inclusion into the main schedule and uploading to the satellite. This arrangement continued until SO-35's demise, and in late 2000 was expanded to include schedulers from several other parts of the world, who were responsible for coordinating transponder activity over their respective regions. SO-35 brought this little group of amateurs from all over the world together.

For a month from June to July 2000, our friend in the sky was off air, suffering a bit of "sunstroke" as its orbit became fully illuminated by the Sun. Amateurs down here were constantly asking for news on the satellite, as by this time, I had close ties with the SUNSAT team, and was overn the first in the area to get news. By July 8, the SUNSAT team were able to get SO-35 back on the air, this time in Mode J. SO-35 for some reason never seemed to perform as well in Mode J, and in August/September 2000, I assisted the SUNSAT team with tests on the transponders using various configurations. My minimal station configuration was ideal for comparing weak signal performance of the satellite, and I also had UO-14 as a benchmark to compare SO-35 against. This was a period of feeling like part of the SUNSAT 'family'. During this period, we also conducted tests on an experimental dual channel configuration. While this mode worked, it also made the satellite very deaf, and was never used anywhere outside of the Aussie experiments.

In October 2000, w saw parrot mode officially for the first time. This proved to be a popular, if sometimes frustrating mode to work. SO-35 always had a trick up its sleeve. It was an amazingly versatile bird. Of course, for most of 2000, while SO-35 wan't being used for voice, it was busily relaying APRS packets all round the world, with a lot of success. This APRS relaying was appreciated by many people and will also be sadly missed.

Mode B returned to SO-35 on October 11, 2000, and this return heralded probably one of the most fun parts of SO-35's operational life that I can recall. By this time, the orbit had begun to coincide with my train and tram travel home from work, so I was frequently able to operate from a tram or train after work! Many amateurs scored an 'eQSL' for working me during this period. With the assistance of that incredible Mode B transponder, tram and train mobile operation became routing, and portable operation was like using a mobile phone, just pick up the radio and talk!

The new millennium promised much, as SO-35's capabilities grew. By January 2000, I was able to specify not only the time, but also the mode and duration of the passes. Unfortunately, as 2001 dawned, various hiccups caused the schedule to be a bit erratic, and as it looked like things were going to get going, then everything stopped.

SO-35 was a big influence on my amateur radio activities, rekindling my interest in satellites and it also taught me more than simply how to work a satellite, but some basic orbital mechanics and other considerations of operating a spacecraft, through my involvement with the SUNSAT team. I, and many amateurs will miss SO-35, and I will also miss the regular contacts with the guys who operated it. They are one of the nicest bunch of people to work with. Thanks guys for the opportunity to work with you, and hope to be able to help out in the future.

I look forward to any future satellites that the SUNSAT team may turn out and wish them every success with their endeavours.