Always unpleasant noise pop T/R


Gerard
 

Hello,
Despite having modified my mounting and added some elements (Diode + resistance +capacitor) on the mosfet from the foot 25 of the arduino (T/R), I still have unpleasant noise during reception/ emission swap tests.


I looked at the oscilloscope to see how the RX and TX power supplies were switching.
I realize that, in fact, the rise in tension is almost instantaneous when we flip, but the descent in tension is not immediate, especially for part TX.
Which means that at each flip, we can have the RX powered, and again the TX for for several hundred milliseconds (Probably discharge capacitors)
So it translates as a shot of a gun or flush in the top (Each chooses. LOL)
I do not know if it is due to fat that the PA part is not cabled ?? I don't made emmision at this time.
So my question is: How to make the voltage on the TX alim drop very quickly.
Cabling resistance in parrallele on each chemical or other? A system with diodes?

Then you can say, that it is useless when we do not make a broadcast, (So no flip) but it is for the principle of finding a solution. I don’t know if the problem is 100% solved for you.

Thank you for your answers.
nb: The control of the tx/rx relay is perfect
cdt

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