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Topic: Problem with YK04 (Read 405 times) previous topic - next topic

Nico_2121

I have mounted an RF receiver marked YK04 that has an integrated PT2272-M4 (with its corresponding 4-button remote control) to activate a relay. Everything is powered by 5V.

The assembly works perfectly, except that for the control to work it has to be less than two meters from the receiver when both in the specifications of the merchants and those found in google say that up to 15 without an antenna being the test also without walls in the middle.
I have searched the internet and tested several antennas with measurements made with precision gauge, fine cable and thick cable, both coiled and straight (I have even used one of a radio that had a scrap) and both in the transmitter and the receiver but the maximum I have reached is up to 3 or 4 meters and not always.
I have also powered the emitter from an external source but there were no changes.
 I have tried all this with 3 different modules with their respective remotes, with new batteries, and the same thing happens.

Is it a bad lot problem? Sellers don't tell the true specification?
Could someone fix it?

From already thank you very much!

steve_mcdonald

There are a lot of things that affect RF transmitters' performance and what you're seeing isn't unusual with the cheaper transmitters.  With the correct antenna, gain will be improved and with it, the performance over distance.  Note also the necessity of filtering the power supply as noted in the datasheet. 

To size the antenna you need to know the transmitters carrier frequency, since the correct length antenna depends on wavelength (1/frequency).  With these types of transmitters, a piece of straight wire of the correct length will likely improve performance to a few metres, but I suspect 15 metres through walls is a bit optimistic (and the wall type matters for RF permittivity as well).  From the datasheet "The antenna has a great influence on the receiving effect of the module. It is better to connect the 1/4 wavelength antenna. Generally, a 50 ohm single-core wire is used. The length of the antenna is about 23 cm for the length of 315 M, and about 17 cm for the 433 M. The position of the antenna also has an effect on the receiving effect of the module. When installing, the antenna is as straight as possible, away from the shield, high voltage, and the
source of the interference."

In short, a straight wire antenna of the correct length for your frequency will improve matters, but it's not easy to say how much. 

The other possibility is to tune the transmitter and receiver accurately.  Each transmitter is factory tuned, but you may find fine tuning will make a difference, as they are not necessarily tuned in pairs.  Tuning is very delicate, since the Q-factor (the tuning factor, more-or-less the sharpness of tuning) is usually quite sharp and peaky for these units.  If you're not familiar with RF tuning you probably want to resist doing that, unless you have the right tools and knowledge.  If you did want to, the tuning element is the green plastic box with the slotted screw in it, but again be delicate, small movements, mark where it is exactly before you start, and count turns so you can get back to the factory setting if needed.

Nico_2121

Thank you so much!!
I am a noobs in RF and I will follow yours advices.

Only I must investigate how to make the 1/4 wavelength antenna.
I will try later and tell you.


Regards.

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