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sBitx temperature problem #bitx20

 

From my radio comes emanation that makes my eyes burn and give me headache. Aside from that the radio is working great.
?I did remember that I still have an IR camera from my working days and did open the radio. Very nice layout. I also took the opportunity
to install the RTC battery.
A few spots are showing above 70C and even 82C. That is in receive mode only.
See pictures.

20230430T111053.JPG

 

Yvonne,
please clarify which parts of which radio have high temperatures.
The information is lost in the details and I don't recognize all of them.
Maybe if you post a photo of the same part.
--
Gyula HA3HZ
 

Is that the tcxo??
 


I hope this helps:

Temperature on this one is 83.1C



the temperature on this one is 73.7C
 


Yes, it can be easily identified that way. I wonder how this temperature could be effectively reduced.
There is no space for a cooling surface, possibly a series resistance to the regulator input.
--
Gyula HA3HZ
 

on the regulator I was thinking of attaching a small heat sink with nut, bolt and loctite.For the clock generator, like mentioned by somebody else there is a risk that the heat sink attached with sticky thermal pad might get loose and
destroy a lot of things. I was also thinking about a small heat sink with sticky thermal pad but secured with some epoxy glue on each side. For the time being I'll temporarily install a small 12v fan outside on the left side above the power plug.
I am open to any suggestions/
 

a resistor will dissipate a lot of heat too. But this gives me the idea of using a voltage regulator ahead of this one to reduce the input voltage and the dissipation. A better solution would be a small switching regulator module but I am afraid it might
generate RF noise in the system.
 

Yes, it is possible that the 9V regulator built between 13.5V and 5V divides the heat generation.
--
Gyula HA3HZ
 

Gyula, I did order some L7809, TO220 heat sinks and some heat sinks with thermal pads for the clock generator but will secure it mechanically so it doesn't fall off.
I should receive them Tuesday and will report how it works.

73, Yvon AE7YD
 

Linear regulator could be armed with heatsink I guess. Looks like there is enough space around.?

-P #5
 

Yvon,

Both of the "hot" devices are regulators.? One is the regulator for the Raspberry Pi; the other is for feeding the AMS1117-3.3 regulators.? What some are calling the clock chip is the switching regulator that is used to power most of the digital circuits.

A sick on heatsink could be added to the IC on the switching regulator, but it should not be needed.

73
Evan
AC9TU
 

Gyula,

I don't know the current that goes though the 5v regulator but if we take for example 100mA, in the case of just the 5v regulator the dissipation would be (13.5 -5) x 0.1 or 850mW. If we use two regulators
the dissipation for the first one would be (13.5 - 9) x 0.1 or 450mW and the second (9-5) x 0.1 or 400mW. A major reduction of heat dissipation.

Yvon AE7YD
 

thank you for clarifying that Evan.
As for the temperature, if the temperature measured of the packaging of the chip is 83 degrees C it means that the die temperature is much higher and out of spec.
 

Here is what I believe to be the equivalent:


The specification states that up to 1.5 amps and no cooling is needed.? Cooling should be added to the regulator chip if the current requirement is the full 3 amps.? I would put a stick-on heat sink like this:


I am not at home to validate the size.? Measure the IC on the regulator and get a heat sink that matches.

73
Evan
AC9TU
 

Evan.

like others mentioned double sided heat transfer tapes are not the most reliable for adhesion. In fact I added two heat sinks on my FX-4C and one is often coming loose.
Not a big problem there as it is mounted on the top outside the radio but in the sBitx it is vertical and inside the radio.
Your link shows the ones I did order last week and they should be in tomorrow.

Thanks for the help..

73, Yvon
AE7YD
 

I missed your info on the switching regulators. I used similar ones in previous projects at work. I have to check if I still have one. If not I'll order the one you refer too.


73, Yvon
AE7YD

?
 

I looked at the drawings and recommendations of the STDN-3A24 module and noticed that the value of several components changes depending on the output voltage. The first thing to notice is that the value recommended for the 5V 3A output in the photo is not the same as the value of the inductance. According to the label, the built-in inductance is 100.
According to the recommendation, 5.5uH I saw a value of 4R7 elsewhere. These are the recommendations of the MP2315.
Could that be why its heat production is higher?
--
Gyula HA3HZ
 

For what it’s worth, I plan to add a 12VDC fan to the top of the DE enclosure. ?The RPi in my machine gets warm and I plan to locate the fan just above it. ?Cool air will pull in from the sides and I am thinking about adding an internal shelf to add a Lipo battery and to add an air baffle to route cool air. ?Since the 5VDC regulator is mounted vertically right next to the left air vent, it should get plenty of air. ?For insurance, I’ll pop on a heat sink.

I’ll post pictures when finished.

Scott?
 

Scott,

Run the 12V fan on 5V and it will very silent.

Raj

On 02-May-23 6:53 PM, Scott KE8KYP wrote:
For what it’s worth, I plan to add a 12VDC fan to the top of the DE enclosure. ?The RPi in my machine gets warm and I plan to locate the fan just above it. ?Cool air will pull in from the sides and I am thinking about adding an internal shelf to add a Lipo battery and to add an air baffle to route cool air. ?Since the 5VDC regulator is mounted vertically right next to the left air vent, it should get plenty of air. ?For insurance, I’ll pop on a heat sink.

I’ll post pictures when finished.

Scott
 

i second that ... on my 13cm amp for qo100 i run a 12v fan on 5v (just enough to start) and its near unhearable

greetz sigi dg9bfc

Am 02.05.2023 um 17:12 schrieb Raj vu2zap:

Scott,

Run the 12V fan on 5V and it will very silent.

Raj

On 02-May-23 6:53 PM, Scott KE8KYP wrote:
For what it’s worth, I plan to add a 12VDC fan to the top of the DE enclosure. ?The RPi in my machine gets warm and I plan to locate the fan just above it. ?Cool air will pull in from the sides and I am thinking about adding an internal shelf to add a Lipo battery and to add an air baffle to route cool air. ?Since the 5VDC regulator is mounted vertically right next to the left air vent, it should get plenty of air. ?For insurance, I’ll pop on a heat sink.

I’ll post pictures when finished.

Scott

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