Questions about FS1000A and MX-RM-5V RF transmitter/receiver

[HisDudeness]

Hello everyone! I want to control an RC car using Arduino-compatible boards, so I bought some cheap 433MHz modules. However, I have some questions about it (I am not able to find a datasheet):

• My receiver is named MX-RM-5V instead of XY-MK-5V, like I read anywhere else. Since my module name gets me no result on the internet, does anyone know that and can tell me the differences, if any?
  

• All the images of the transmitter I find have a coiled copper wire I shy. Is that important? What does it do?
  
  

• The hole I should solder the antenna on the receiver is soldered shut. Should I think nothing of it and just melt the solder, attaching the antenna like if the hole was left free?
  

• What does the little knob in the green cube do in the receiver? Maybe I'm a lousy searcher, but I didn't find the datasheet, nor specific answers for that.

Thanks, a good day to you!

[virtualmkr]

@HisDudeness Hi, MySensors will not help you with your use case to control a RC Car.
But may be this link helps you further:
rf-433mhz-transmitter-receiver-module-with-arduino

[HisDudeness]

@virtualmkr Thanks for your answer, but I didn't ask for help on my project, just those four questions. To summarize, what's the coil I miss for, why the different receiver name, what's the screw for and if I should ignore the antenna hole being soldered. Thanks again!

[virtualmkr]

@HisDudeness Your module does not have the coil because the Chinese manufacturer decided to make production costs for the cheap module even cheaper. Technically, these coils serve to suppress harmonics of the transmitter. Without the coil, your module also transmits on a frequency other than the one printed on it.
Here in Germany, for example, it is strictly forbidden to transmit outside the ISM frequency band 433 MHz without a licence. This is also controlled and, if necessary, prosecuted.

[HisDudeness]

@virtualmkr Oh, man. Here in Italy too, AFAIK. So, it would be a good idea to add it? Is it really just a coiled copper wire that I can do myself?
Also, is the knob to calibrate the frequency?