Short-range (10') AM-band transmit from 3.5mm Android headphone jack

Using Arduino Audio
17

Ok I'm using 47uF capacitor interfacing with 100K resistors as you suggested & A0 pin input and getting 485 reading with audio off, and 520 - 460 range with audio on. Still no music reception on AM 530 although pin 9 is definitely transmitting something as proximity to antenna is affected only at that radio frequency (static / hiss). Here's updated code. (I commented out Serial.println to test radio reception.)

int audioPin = A0; // positive lead from 3.5mm phone headphone jack; other lead to GND

const byte ANTENNA = 9;
int val = 0;

void setup() {
  Serial.begin(9600);
  pinMode(ANTENNA, OUTPUT);
 
 // set up Timer 1
 TCCR1A = _BV (COM1A0);  // toggle OC1A on Compare Match, Timer Interrupts
 TCCR1B = _BV(WGM12) | _BV(CS10);   // CTC (clear timer) no prescaler
 OCR1A =  14;       // 530 kHz

}

void loop() {
  int sensorValue = analogRead(audioPin);

  //Serial.println(sensorValue);
  
  digitalWrite(ANTENNA, sensorValue);
}