I have this RF remote control that I'm trying to understand (here is spec: http://www.telran.co.il/images/980305%20QK-M04%20TECH%20SPECS.pdf ).

I recognize crystal oscillator that is responsible for getting required frequency of the signal, I understand how this hcs301 chip provides KeeLoq encryption, I recognize a battery as a power source ;) . But what here is actually generating the radio signal? I cannot find anything resembling an antenna here, and this remote has quite a long range (about 100m).

Could someone find an antenna here and explain what component(s) is responsible for generating an actual radio signal in this device?

back front #1 front #2

  • 1
    \$\begingroup\$ At first glance, this appears to be an infrared remote rather than radio. Note the LED (marked D3) at the end of the remote (opposite end to the crystal). \$\endgroup\$ Jan 27, 2020 at 23:02
  • \$\begingroup\$ first picture, bottom trace appears to be the antenna \$\endgroup\$
    – jsotola
    Jan 27, 2020 at 23:12
  • \$\begingroup\$ @DwayneReid It's radio one for sure, I'm using it to open my gate. :) and look at specs, the name of this model is actually also printed on PCB. \$\endgroup\$ Jan 27, 2020 at 23:14
  • \$\begingroup\$ @jsotola This wider path? Actually it is indeed coming out of the oscillator so I think you got it, I didn't know antenna can look almost like a normal path. \$\endgroup\$ Jan 27, 2020 at 23:18
  • \$\begingroup\$ "I didn't know antenna can look almost like a normal path" - and 'normal paths' don't usually look like antennas, but they often are (unintentionally). \$\endgroup\$ Jan 27, 2020 at 23:42

1 Answer 1


Looks like a 433 MHz oscillator, transistor "R25". The trace that likely radiates RF is around the perimeter, in yellow on the "bottom" side of the PCB:
enter image description here The transistor collector is fed DC battery voltage through "L3" marked in yellow.


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