# Test circuit to confirm RF receiver frequency? (315Mhz vs 433Mhz)

I've bought a 433 Mhz Transmitter/Receiver pair, or so I think. I cannot make them work, and I started to think that maybe the seller sent me a 315Mhz transmitter / 433 receiver pair by mistake (I've seen people online complaining about things like that, mainly because both types of modules look exactly the same and are easily confused apparently).

Here is a picture of my modules:

As you can see, the transmitter module (the one on the left), has a "R315" engraving. This suggests me this is indeed a 315Mhz transmitter. Is that so? I've seen pictures online of other transmitters with a "433" mark, so probably yes, I guess...

Now, the receiver module (the one on the right) does not have any special engravings or marks. On the back side it reads "XY-MK-5V" (which I googled but many articles are about "315/433 modules" so I don't think that's conclusive):

It also shows a table with three values "315Mhz", "330Mhz" and "433Mhz", but none looks specially marked.

How could I test in which frequency this receiver module is operating? Is there a simple test circuit I could build to do that?

Thanks!

• The receiver is a regenitive receiver, you can directly measure its LO freq with scope/counter/ sdr etc Aug 26, 2017 at 22:16
• @NickAlexeev clarified title. I'm interested in what type of test circuit you can build to confirm a receiver working frequency, assuming information from seller is not available and datasheets are missing or ambiguous on this. I'd appreciate removing the hold on the question since this makes the intention clear. Also a "we are not your technical support" statement is totally uncalled for IMO. Aug 27, 2017 at 1:38
• I own one, but can you find a spectrum analyzer? You could check the transmitter frequency with one. I feel your pain with random Asian modules.... Aug 27, 2017 at 2:06
• They make very cheap USB based SDR spectrum analyzers. Grab one on EBay and check the transmitter. You really need a spectrum analyzer for RF design. Aug 27, 2017 at 2:44
• The repurposed tv tuner as sdr's, rtl-sdrs are approx 20 dollars Aug 27, 2017 at 2:54

Source: // https://www.pjrc.com/teensy/td_libs_VirtualWire.html