Push To Talk? The Portapack can also be used as a standard Push to Talk or voice activated walkie talkie radio by using the 3.5mm audio jack. With the microphone plugged into the audio jack, simply press and hold the right button to push-to-talk. Capture & Replay Wireless Signal? One of the best things about the PortaPack is that it can easily capture and replay wireless signals like those from ISM frequency remote controls. NFM & WFM Audio Signal? Our Radio Receiver is equipped with 3.5mm audio jack, which makes you listen to standard NFM and WFM radio signals easily by connecting the speaker to it. Easy To Use? This SDR Radio Receiver is easy to connect and install. Press the black knob once to turn on and twice to turn off.