How to increase thermal shutdown from 50ºC to 60ºC for the Radioberry Preamp?

Samuel Lourenço

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Nov 4, 2024, 6:18:32 PM11/4/24

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Hi,

I've modified the Radioberry Preamp, adding two aluminum bars as head spreaders and an heatsink. Although the thermal performance improved a lot, it still shuts down after a while. However, it seems that I have the conditions to increase thermal shutdown, as thermal conductivity between the output transistors, and from those to the thermal sensor is much improved.

The question is, how I can increase the thermal shutdown to 60ºC? Also, what compiler tools are required? What code should be changed? How can I recompile?

Kind regards, Samuel Lourenço

Yado-san

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Nov 8, 2024, 8:57:26 PM11/8/24

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Hi Samuel,

I would recommend using a suitable heatsink, but I also changed the firmware temporarily.

* The compile and install process is described in radioberry_install.sh

https://github.com/pa3gsb/Radioberry-2.x/blob/master/SBC/rpi-4/releases/dev/radioberry_install.sh#L127

sudo systemctl stop radioberry
git clone --depth=1 https://github.com/pa3gsb/Radioberry-2.x
cd Radioberry-2.x/SBC/rpi-4/device_driver/firmware
sudo make
sudo cp radioberry /usr/local/bin

* The temperature settings are in firmware/radioberry.c

https://github.com/pa3gsb/Radioberry-2.x/blob/master/SBC/rpi-4/device_driver/firmware/radioberry.c#L501
line 501-521 ( 60C: 1256 -> 1382 )

static void *rb_measure_thread(void *arg) {
// temperature == (((T*.01)+.5)/3.26)*4096 if pa temperature > 50C (=1256) switch pa off! (pa_temp_ok)
int measured_temp_ok_count = 0;
while(1) {
sem_wait(&i2c_meas);
if (i2c_measure_module_active) read_I2C_measure(&pa_current, &pa_temp);
if (pa_temp_ok && (pa_temp >= 1256)) {
fprintf(stderr, "ALERT: temperature of PA is higher than 50ºC; PA will be switched off! \n");
pa_temp_ok = 0;
}
// PA recovery after high temperature; switch PA on again if PA temp is in range for 10 seconds.
if (!pa_temp_ok && (pa_temp < 1256)) measured_temp_ok_count++;
if (measured_temp_ok_count == 100) {
measured_temp_ok_count = 0;
pa_temp_ok = 1;
fprintf(stderr, "PA temperature is ok; PA can be used! \n");
}
}
fprintf(stderr,"rb_measure_thread: exiting\n");
return NULL;
}

hope this helps

Yado-san, jg1twp

2024年11月5日火曜日 8:18:32 UTC+9 Samuel Lourenço:

Samuel Lourenço

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Nov 9, 2024, 11:15:02 AM11/9/24

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Thanks, Yado-san,

I was under the impression that the steps required to install Radioberry from Git would already require the compilation of source code, but I have to revisit that and do as you indicated. I'll also have to clone the SD card and try that.

As for suitable heatsinks, do you have any suggestions? I've had to makeshift one, as you read, but although the improvements were clear, it is still underwhelming.

Kind regards, Samuel Lourenço

Joey G. (Bonehead)

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Nov 9, 2024, 8:23:07 PM11/9/24

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Has anyone tried putting bigger transistors to see if they are better at handling the heat? I have put heat sinks on mine as well but still get the temp shut down. It doesn't trasnmit long enough to do a FT8 transmission. I have not changed the temp settings though.

wim

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Nov 10, 2024, 3:08:41 AM11/10/24

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Van: