Final Transponder Design


On this webpage I show some pictures of the MODE-UV transponder what I made for P3e of AMSAT-DL.


The MODE-UV transponder has a RX and TX PCB.



Input : Lineair (all mode) 70cm UHF

Output : 2x 10,7MHz IF wide-band for command radio and RUDAK uplinks.

: 2x 10,7MHz IF narrow band (100kHz) for transponder use (downlinks on 2m and 13cm)

Extra : AGC circuit and radar protection circuit



Input : 4x 10,7MHz IF from: RUDAK, Beacon, 70cm RX, 10m RX

Output : 2m VHF Split into a phase (10mW) and envelope (amplitude) signal for the HELAP PA.


To have more experiments on board of the P3e satellite space is needed and therefor the transponder has been designed to be very small in size. This has been done by using SMD technology. The components used are 95% 0805 size SMDs.


The inductors are self-wound 5mm type to keep height as minimum as possible. Because of the small component height, the RX and TX PCBs can be mount on top off eachother and still fit into a 3cm high box.

The design has been made 3D small sized J


Below some pictures of the transponder PCBs:



A picture of the two flight model PCBs on my working table. (2x TX PCB, 2x RX PCB)



A close-up view



Top view of one MODE-UV transponder



Bottom view of one MODE-UV transponder


73 de PE1RAH, William Leijenaar






73 de PE1RAH, William Leijenaar.

E-mail: [email protected]