Re: IRF510 amplifier failures
toggle quoted messageShow quoted text
Marco - KG5PRT
That is very interesting indeed. Implementing this current based bias control
If I understand this correctly...
- Voltage drop across R1 forward biases T2 to ON state
This lights the LED.
- Voltage on the collector of T2 turns T1 OFF, removing supply voltage
to the 5V bias regulator in the RF PA circuit.
I was looking toward a similar control based on reflected power but the current
based approach is easier, as long as it works. This adds another project to my
Thanks for the URL.
On Thu, Jan 25, 2018 at 10:11 PM, M Garza <mgarza896@...>
Here is another:
In the middle of the page, is this:
"I destroyed many IRF510 FETs during testing. In fact I blew a small hole in one and another into several pieces. It was quite a shock when the first one was destroyed because it made a loud noise like a rifle being fired.
Once I got tired of replacing the FETs, I built a current sense circuit, which shuts off the bias once the amplifier draws more than about 3 amps from the PSU. I think this circuit is essential. You can build it into the Power Supply or into the Amplifier. I built it into the Amplifier because the power supply, which is also homemade, does not limit until 7 amps. With the current limit circuit the amplifier now survives transmitting into any SWR from an open circuit to a short."
There is a schematic for the current limiting circuit that is used. This might be something to incorporate into the design. It is only 7 more parts.
Marco - KG5PRT
Join BITX20@groups.io to automatically receive all group messages.