The ThermoPro transmitter is sending a rh of 38 while the base unit is reading 33 for the same location.
The larger unit is a Growers Edge. You can see the transmitter is sending 43% to the base unit (channel 1). However, the base unit reading itself is 30% (no channel) WTF??
Try this. You want a slurry of salt, not salt water.
Place a teaspoon of salt in a bottle cap or small cup and dampen it with a few drops of water (without dissolving it).
Carefully place the wet salt and the hygrometer inside a see-through container and close tightly. You can use a zip lock bag provided it seals well and you leave some air inside as well.
Let it sit for at least 6 hours and note the reading on the hygrometer without opening the container. The hygrometer should should read 75%. The difference is how much your hygrometer is off. For example, if your hygrometer reads 70% during the salt method test this means that to obtain the real humidity level you should add 5 points.
If you have an analog hygrometer, you can correct the reading. You will need to adjust the needle to the 75% mark by turning the screw on the back using a small screwdriver. Your hygrometer is now ready to be placed inside your humidor.
I need to clarify, I was not suggesting that you should purchase different hygrometers, I use the same ones that you have for my curing tubs.
I was pointing out that these sorts of devices have an intrinsic accuracy and you can expect them to differ within that accuracy range.
The reason that I have the instrumentation grade device is that the device sends a 4-20 ma signal to my controller which in turn controls my fans, dehumidifier and humidifier (that is addition to controlling all of the various lights).
@merlin44@GoneFission@kellydans@Ron330@nicky - I thought I saw you have a ThermPro
When I had both transmitters in the tent I would have swore the ThermPro was the correct reading. Apparently have to add 5%. At least temp is consistent. Put this in For What its Worth category.