Hi,
I've designed a modulator using MX614P for my project of satellite communication (CubeSat). A COTS ALINCO DJ-S45E transceiver was used to transmit data received from the modulator.
However, when I connect the transceiver to my modulator, it would cause fluctuation in the power supply for my modulator. I would like to ask what would be the cause for this situation and how to resolve it?
Thanks in advance.
a) ... is the transmitter running on an outside antenna ? or is the antenna/ dummy load on the workbench beside the modulator board ?
b) ... is the modulator shielded i.e. in its own metal case with feedthrough capacitors bring in power and signal lines ?
c) ... do have appropriate RF decoupling on the DC line on the modulator board ?
a) using the antenna which comes with the transceiver at the moment
b) nope, not using any shielded for both the modulator and demodulator
c) i don't quite understand this
I would also like to ask what is the max normal current input into the transceiver? as i have set the max current limit for the power supply at 0.47A.Thanks =)
ok .... a) if the antenna is in the room and relatively close to your modulator cct say within several metres then you could well be getting RF back into the modulator cct and or PSU this will have all sorts of nasty and weird effects.
try transmitting into a dummy load that is rated in freq and power for the transmitter
Can you give an example?shielding correlated with poor layout design could make things actually worst.
Hi, I just saw the thread. Just to touch up on the problem that my team mate and I are facing now:
a) when I insert the stereo plug (the other end connecting to the output of the modulator) into the DJ-S45E, the power generator that is supplying power to my modulator started to act weird. When I place the transmitting transceiver in a certain angle, the power supply will decreased to a certain low values (the current value varies a lot too) which is not enough to power my modulator. And sometimes when I place in another angle, the power will be back to being enough to supply the modulator.
b) the antenna that we are using is in fact within a metre from the modulator.
So in this case, could the reason still be due to the RF being radiated back to the modulator? Thanks.
yup, that virtually confirms the RF feedback problem. look at some of my previous stated thoughts to overcome the problem whilst testing...
use dummy load rather than antenna, there will probably still be plenty of radiated signal for the receiving unit to pick up.
You can use as a shield even a **broken link removed**.can I use the metal shield to cover my modutor?
Amazing...to test a circuit that will be send in space, wired on a breadboard ...hopefully you are not sending the power supply also...
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