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PE1RAH-SAT V2 (prototype)


Here you can see the last prototype of my second satellite transponder that I designed and made.

This satellite transponder is very small and belongs to the catogory of NANOSATs (<1kg)

After making an Mode-B transponder I find out it you can do lot of funny things with it.

The goal of my MODE-B transponder is to make it light and small as possible to give it more change to get launched

some day. I could make it very small but with getting more experience I started to design an even smaller transponder.

This transponder I wanted to make VERY small. This result in many problems to solve, not only using smaller SMD's

but also finding solutions to reduce the size of the tuning inductors.

Like the PE1RAH-SAT Version1, I used now also the same conditions:

  1. It must be small in size, and leight in weight to get easier an "second payload" place into an rocket.
  2. It must be sensitive and enough output power that it can be used easy.
  3. Good effeciency to get low current (smaller solar+batteries = smaller size) , and low heat production.
  4. It must be temperature stable for good radio contacts.
  5. Radiation proof to get longer life time.
  6. All must be vibiration proof to get no suprises after lauche,
  7. So, no wires , no internal connectors, all no SMD components made vibiration stable.


To make it practicaly possible I had to make it MODE-J (2m up, 70cm dwn)

Below you can see an picture of it:


Right below: 2m GaAs FET RX amplifier.

Right middle: Double balanced mixer.

Right top: First LO (VHF)

Middle below: Second LO (UHF)

Middle top: IF filter + mixer.

Left top: 70cm filter.

Left below: 70cm 1W PA module (not yet)

The total size is 6cm x 4cm x 1cm.





The idea is to put this transponder together with 5 rechargable penlite batteries into an music casset box.


All the tuning inductors are replaced by self wounded inductors !!!

The tuning is done by measuring and then increase/decrease the windings when not good. It tooke me several days

to get everything tuned, because it is very small and it takes lot of patience.


I did test it and it is working only with to less output PWR.

The both LO I did tested till -30C temperature and they were more stable than I expected.

It still takes lot of time and money to finish this project, but some day I will finish it J


This prototype is an lineair MODE-J transponder. (ALL MODE 150 kHz bandwith.)

TX: 435.175 MHz - 435.325 MHz. USB

RX: 145.975 MHz - 145.825 MHz. LSB



Let's hope I will find some lift into space at the end, I will go for it !!!

When you know something, please tell me [email protected]


This page is very new, and the main goal for me is to give technical information, so don't look at my English.


This page is designed and created by PE1RAH. (William Leijenaar).