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Re: Checking irf510

 

César EA3IAV

Your "universal tester" unit is telling you quite a bit about your MOSFETs.? As others
have said, "if it identifies the device as a MOSFET the device is testing as GOOD".?

Because this tester uses fairly low voltages the internal capacitance may show as
fairly high relative to the datasheet.? IRF510 type MOSFETs internal capacitance
decreases as you increase the drain-to-source voltage.? This is why they are usable
into low VHF frequencies when operated at higher voltage.? It is also why they make
very good VVCs (Voltage Variable Capacitors), but that is a story for some other post.

The tester is also telling you what the base bias needs to be to turn the IRF510 ON.
Because this is a MOSFET the tester treats it as a switch instead of as a linear
amplifier, but that test is adequate to tell you if the device is GOOD or BAD.

As mentioned by others, my earlier suggestion that you obtain or build a Diode RF
Probe similar to that designed by is still valid and highly recommended.

Arv? K7HKL
_._

On Sun, Jan 28, 2018 at 6:16 AM, M Garza <mgarza896@...> wrote:
If they all showed as being a mosfet, they are working.? It would show something else, otherwise.
What is the gate voltage, when transmitting?? It should be between 2 & 4 vdc.
I doubt anyone is making a joke about this.? You have to do some detective work.? We do not have access to the board.? Is there someone you know, locally, that can help you troubleshoot?? Have you traced the rf signal in the output stages to see where the signal stops?? It was suggested that you build a rf probe, have you done that?? It will help, immensely.
This isn't something we are going to be able to say, " oh that is such & such part.? Replace that.."? you will have to dig in.? This is not a terribly complex radio.? It is easily fixable.? It was working, but it let out some smoke.? In what area did this happen?? Have you looked at the parts and traces in that area?
We are here to help, but we need you to be thorough and we need as much info as you can provide.

Marco - KG5PRT?

On Jan 28, 2018 5:27 AM, "César EA3IAV" <Cesarleon@...> wrote:
how can i check if a fet is shorted or blown?

i have this piece of hardware but i have no clue if this values are fine

here you have a brand new irf510



here a used one that may be dead but i don’t know...
I checked several that i have used and they have similar values
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