Radiating RF

Can someone please tell me how to stop any radiating RF happening unless actually transmitting. The sketch uses the HC-12 wireless module. The Arduino receiver module shows a fast blinking red LED when idle and I can hear a buzzing noise from my PC speakers. 

I only want to radiate a signal when the button is pressed. Thanks

//HC-12 SEND2 Momentary Button Send

#include <SoftwareSerial.h>

SoftwareSerial mySerial(3, 2); //TX, RX

int buttonPin = 8;
boolean onOff = 0;
void setup()
  pinMode(buttonPin, INPUT);
  digitalWrite(buttonPin, HIGH); // turn on pullup resistors

void loop()

  int buttonState = digitalRead(buttonPin);//read button state

  if (buttonState == 0) //if button is down
    mySerial.println(1001);//send unique code to receiver to turn on. In this case 1111
    onOff = 1;//set boolean to 1
  if (buttonState == 1) //Verifier to send off signal once

Use the button to turn on the power ?

Thanks srnet, I think I will do that, then at least I know it’s safely off during quiet periods. Also I can consider using batteries in the remote control that will last longer.