Is the PCB in use or is it off?

The operating temperature of any PCB is going to be higher than it’s environment because the electrical currents create heat through the part. So if you’re measuring 105C at a powered on PCB, then I would argue the chamber itself is not actually 105C, but lower.

When you say the chamber was set to 105C is it regulating the temperature with a thermocouple that is actually measuring the temperature? If so where is that thermocouple? And where is the heat source? Is there one heat source or multiple? Is the chamber being heated by driving heated air through it? Also how insulated is the chamber?

It seems likely that the air in the chamber isn’t actually 105C. This could be for a lot of reasons, like if the chamber isn’t insulated very well or if the heating element is too small or the heat transfer from the element to the air isn’t very efficient or if the feedback loop that targets a temperature setting has a bias from poor temp sensor placement or calibration. Any or all of these things could lead to inaccuracies in the chamber temperature. And it’s very likely that you don’t actually reach thermal equilibrium no matter how much you “soak” if the chamber is losing heat energy, which it almost certainly is.

Think about a 3D printer, the bed temperature is regulated with a thermocouple that is attached to the bed. If you set that to 105C bed temperature, the air in the enclosure is absolutely not going to be 105C no matter how long you soak for. Because the thermal losses from the chamber are too great.

My guess is that this is what’s happening to your chamber. I’d put an old fashioned thermometer in there with no PCB and see how close the air temperature is to the setting after a 30 minute to one hour “soak”

Edit: if you want to tell me more about the chamber (ie answer some of my questions about how it’s heated) I can help get more specific. Also knowing what the chamber exterior is made of would be helpful.

It’s not a pressure wave. It’s an entirely different mechanism.

The fork tines oscillate back and forth as the metal bends at the base of the tines. There is no propagating wave through the metal. It’s really more like the motion of a spring.

Not all vibration crates sound and vibration is never sound in and of itself.

All atoms are vibrating all the time. But they are so small and there are so many of them vibrating out of sync with one another that a pressure wave never develops in any given direction.

Noise canceling headphones cancel the noise by oscillating out of phase with a sound wave so that the sound wave is canceled. So that’s a case where vibration actually eliminates sound.

Vibration is not sound.

I’m trying to make the distinction that it is not sound in a vibrating fork. The sound is what happens when the vibration of the fork is translated into a medium as a pressure wave. So there is no sound in the fork.

The other answers about communicating are correct, we use radio wave which are light and which do not require a medium to propagate.

We freeze in space because there are no molecules in the air (there’s no air) bumping into our skin. On earth, air molecules are constantly bumping into you and transferring the energy they have picked up from the suns rays or from other air molecules. When this happens your badly stays warm.

But if you go to the top of a mountain, even in a sunny day it’s really really cold because the air is very thin. Actually you might be warm on the top of the mountain if you were in the sun because the suns rays would heat you up but if you were in the shade you’d get real cold. Even the back side of you body, the part not facing the sun would get real cold.

This is what happens in space as well. Things that are in direct sunlight are very hot and things that are in the shade are extremely cold. Because the only natural heat source when there is no air are the rays from the sun.

The James Webb Space telescope is over 200 degrees Fahrenheit on the sun lit side and is less that -350 degrees Fahrenheit on the dark side. There is almost a 600 degree difference. All because there is no air.

Definitely no sound in space. If you watched an explosion in space, it would be silent until the moment the edge of the explosion reached you and then it would be chaos. Because explosions are (usually, depending on what exploded) made of gas that will carry sound.

It’s not actually sound. It’s vibration. Sound is a propagating wave. The fork oscillates and when you put your face on it you’ve given the vibrations a medium to propagate through. Even if you put your ear drum directly on the fork the vibration would cause the ear drum to oscillate and then a sound wave would form in your cochlea (inner ear).

The fork is vibrating. It’s never causing a pressure wave through any adjacent medium. The fork itself has energy but if it was truely in a vacuum it would never make any sound. Vibration is not the same as sound.

I wasn’t saying that the fork energy ceases to exist at the boundary of the fork, it’s just not translated into any matter as the fork oscillates back and forth through empty space. It is the atomic structure of the tuning fork itself that will cause the vibration of the fork to eventually stop. With every oscillation of the forks tines the amplitude gets a little bit smaller and the energy witching the fork translates to head which is radiated away. Or conducted away through whatever is holding the fork.

None of this is sound though. Sound is a pressure wave propagating through a medium, by definition. A tuning fork normally makes sound when there is air around it because the oscillating of the fork causes alternating low and high pressure in the adjacent air. This is the part that can’t happen in a vacuum.

A sound doesn’t have any energy of its own, it’s all kinetic energy of interacting matter. So when a sound wave from earth reaches the edge of the atmosphere, the molecules will just not bump into another molecule and the sound wave ceases to exist. But the molecules all still have their kinetic energy. And eventually that will dissipate as heat.

The person who talked about the tuning fork is right. I’ll add, though, that that tuning fork in space technically never made any sound because there was no medium for the vibration of the tuning fork to propagate through.