On April 18, 1952, during the "Courier's" shakedown cruise to the Panama Canal Zone, using the call sign KU2XAJ, tests were performed at 1700–2300 on 6110 and 9690 kc. shortwave (35 kW), and 1510 kc. medium wave (150 kW). The broadcasts closed with the playing of the Panamanian National Anthem and the Star Spangled Banner. The "Courier" initially used a $18,000 35' × 69' barrage balloon that held the medium wave antennae aloft. The "Courier" carried 5 of these balloons, but on more than one occasion the balloon broke free. Eventually it was decided to replace the balloon with a mast-supported wire antenna.