JohnJohnCat
- Jan 10, 2019
- 6
- Joined
- Jan 10, 2019
- Messages
- 6
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: 5V&4A, PSU2: 12V&1A, PSU3: 24V&2A, PSU4: 5V&2A. I do work with them normally so I guess the problem is on the load. There is not a shortircuit, the load seems reasonable for the output power (very reasonable,...)
The load is an output stage of a JFET transistor for a UHF amplifier. Regardless of its state (OFF, LINEAR, SAT), I think I should read the nominal value of the PSUi on the terminals but this does not happen.
As attachment, there is a picture detail of the PCB and the behaviour of one PSU. Should anyone have some interest in checking the others just let me know but are "similar" waveforms, dropping to zero.


Thanks for your support.
Receive best regards.
[Mod edit: tidied up picture mess]
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: 5V&4A, PSU2: 12V&1A, PSU3: 24V&2A, PSU4: 5V&2A. I do work with them normally so I guess the problem is on the load. There is not a shortircuit, the load seems reasonable for the output power (very reasonable,...)
The load is an output stage of a JFET transistor for a UHF amplifier. Regardless of its state (OFF, LINEAR, SAT), I think I should read the nominal value of the PSUi on the terminals but this does not happen.
As attachment, there is a picture detail of the PCB and the behaviour of one PSU. Should anyone have some interest in checking the others just let me know but are "similar" waveforms, dropping to zero.


Thanks for your support.
Receive best regards.
[Mod edit: tidied up picture mess]