The final PE1RAH-SAT V1

The idea of me was to make an lineair satellite transponder, because todays new amateur satellites often can only do FM modes, or PACSATs where the mode is only packet radio. With an lineair transponder you can do lot of more experiments, and it is much more fun to have an analog contact in voice or send SSTV pictures, or do RTTY, or what ever mode you like to do.

I am an student telecommunica-tions and I like my hobby because of the elektronical part. My interrests are space com-munications in the VHF and up area. I want to be a designer of space TRX after finishing my school. I did already made 3 local FM repeaters, and now I wanted to make an analog transponder. I tried to find some interrested people. At my school I find none, and in the local amateur world I found nobody interrested in satellite, and not with such elektronical level of knowledge. So, I started to do it by my own, I already designed 3 local FM repeaters. So why not designing an satellite transponder ?


About one year ago I started with the project. I wanted to make an transponder that has little chance to fail.

I started to read about failed satellite missions and I took special attention to the causes of satellite failures.

With this information I made a list of conditions what my transponder has to be capable of.

It must be small in size, and leight in weight to get easier an "second payload" place into an rocket.

It must be sensitive and enough output power that it can be used easy.

Good effeciency to get low current (smaller solar+batteries = smaller size) , and low heat production.

It must be temperature stable for good radio contacts.

Radiation proof to get longer life time.

All must be vibiration proof to get no suprises after lauche.

Several months ago I had an prototype that finally was functioning as I wanted. Then I copied the prototype and with new components I made the final transponder. After testing the final transponder at home by measuring it, and later together with my satellite friend Dirk ON1DLL making qso in sevaral modes for long period, the designing and testing part was ended. For me it was an project to get more experience in designing and how to make an satellite transponder. The next step is to get it somehow into space and lett it be operational for all amateurs. To finish it as an real satellite I need solar cells and batteries that can handle space enviorment. These solar cells are to expensive for me, but maybe there are amateurs who can help.

Some details about my transponder…

My Transponder is an analog amateur MODE-B transponder.

Uplink : 435.200 MHz - 435.300 MHz. LSB.

Downlink : 145.950 MHz - 145.850 MHz. USB (2 Watts PEP).

Beacon : 145.825 CW.

Power : 12 Vdc.

Connectors : SMA (small and less chance to disconnect due to vibrations).

Name : PE1RAH-SAT1


Right below : 70cm RX amplifier.

Right middle : CW beacon.

Right top : 2m PA.

Middle below: Mixer + IF stage.

Middle top : 2 Local Oscillators.

Left : 2m driver.








Most of the components are SMD to make the transponder as small as possible and vibration proof.

All units can be 100% shielded to avoid oscillations and interference of other units. On the picture only the left top and below units are shielded. The other units are opened to show the components.








The connectors are SMA type, to be sure that no disconnection will occure due to lauche vibrations.











On the left the MODE-B transponder.

On the right the 2nd prototype of my nanosat MODE-J transponder.

It is still in designing stage.









This is myself holding my both transponders.

I hope to succeed the final stage, and make an real satellite of the MODE-B and maybe in the future I can introduce an MODE-J nanosat.

My special thanks to Dirk ON1DLL who helped me with testing the transponder.

I am very interrested in satellite techniks, specialy in the V/U/SHF area and I am looking for satellite-groups that like to share information with me….

People who are interested can look at my web-page:

Or contact me via:

73 de PE1RAH, William Leijenaar.