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  1. J

    Too much ripple on a UHF amplifier using JFET transistor

    Hello Davenn. I think, as you say, it comes from the PSU. But not because of it; Just because a radiated interference couples on the DC cables. I say this because even having the PSU off (but connected), the intererence was there. At the moment of disconnecting the DC bananas the interference...
  2. J

    Too much ripple on a UHF amplifier using JFET transistor

    Hello all. I have implemented for first time an amplifier. It seems to work quite well, under my specification. But I am facing too much ripple. It is the first (of two) stage of a 25dBm power amplifier with 787MHz cut-off frequency. The gain seems to work as expected but still pending to...
  3. J

    Switched power supplies - 0V with load.

    Hello Davenn. Thanks for your support. 1) + 2) The PSUs are commercial ones... I mean not professional ones. Find a picture attached with specs (5V-4A & 2x 5V-2A). I do normally work with them with many other devices. I already reported on post #1. 3) I won't be able to get the these...
  4. J

    Switched power supplies - 0V with load.

    Hello all. As promised, here I com with the results. I have increased the load (of the power supply) by adding some resistors in paralel at the input of the DC feeding connectors. Again, the same results. Two different PSU have been used. The funny thing is that these switched PSU can feed...
  5. J

    Switched power supplies - 0V with load.

    Dear Dave. Thanks for your reply. I have also thought about this possibility, but did not guess it could affect. With the linear PSU i read a demand of ~30mA (by memory). I meant SATuration, one of the possible states of the JFET. In this circuit, I expect Vds=12Vdc working in the linear...
  6. J

    Switched power supplies - 0V with load.

    Dear all, I am facing a strange case that hope you can give me some keys. When I use a linear power supply, all is ok. But when I use up to 4x different commercial adapter-type power supplies, the voltage I read on the terminals of the load is zero. These are the nominal values of them: PSU1...
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