According to the official history of PBS, the Philippine Broadcasting System in the Philippine Islands, the first programming from OWI the Office of War Information in Los Angeles California, and VOA the Voice of America in New York City, was on the air from a low powered mediumwave transmitter aboard an American submarine in the Lingayen Gulf, off the west coast of Luzon Island. This unique radio broadcasting station operated with just 50 watts under the callsign KZSO, and it took to the air in its Philippine service in December 1944.
Back during that era, AFRS the American Forces Radio Service, had developed a small portable radio station that could be packed into five suit cases, complete with a mediumwave transmitter, gramophone turntable, music library, pre-recorded radio programs, and a shortwave receiver. It would seem evident that the Philippine submarine operation with OWI-VOA programming under the callsign KZSO was on the air with the usage of one of these very portable, very unusual, and very small mediumwave radio stations.
Two months later, portable station KZSO was removed from the American submarine in Lingayen Gulf and taken ashore where it was quickly reassembled and reactivated again, on February 3 (1945). As the American armed forces advanced south, down towards the 100 miles distant city of Manila, portable KZSO was, as the PBS document stated, “alongside the American soldiers”. And apparently it was also activated at times during that month long campaign.
Initially, after the American forces captured the almost totally devastated city of Manila, mobile KZSO was activated temporarily from a makeshift studio in an old warehouse operated by Carmelo & Bauerman on Azcarraga Street (now Claro M. Recto Street), adjacent to the Far Eastern University.
However soon afterwards, a new composite radio broadcasting station was assembled, using the available leftover equipment from a Japanese radio station, as well as from abandoned AFRS stations, and the mobile KZSO. This new station was inaugurated in May 1945 as an OWI operation with local program productions and a relay on shortwave from VOA in California. The new VOA relay station now with 5 kW on 710 kHz was installed in the Ramon Roces Building on the corner of Soler & Calero Streets in Santa Cruz, Manila, a historic commercial building that has since been rebuilt and modernized.
Initially the suggested callsign for the composite new VOA mediumwave station in Manila was KZRM, with the K & Z indicating Luzon Island in the Philippines and the RM indicating Radio Manila. However Radio Manila with the callsign KZRM was a legitimate commercial mediumwave/shortwave radio station in prewar Manila, and it was likely to be reactivated, so another callsign was taken instead, KZFM.
That composite radio station is recognized as the first mediumwave station on the air in Manila after liberation, and it was allocated the America callsign KZFM: K = Philippines (back then), Z = Luzon, and FM honored Frederic Marquardt, a personal friend of General Douglas MacArthur, a fellow American who had been a prewar newspaper editor in Manila. The (probably informal) callsign of the submarine radio station KZSO: K = Philippines (back then) and Z = Luzon. The SO actually had a double application, as Submarine Operation, and also honoring Sergio Osmena, a Filipino friend of General Douglas MacArthur.
This first OWI-VOA radio facility in the Philippines under the two consecutive callsigns KZSO and KZFM was simply a temporary fill in operation during the construction of a new station at Malolos which was taken into service in March 1948. This composite station was on the air for just a little over 3 full years, and at the end of its tenure, three transmitters were in use.
The mediumwave transmitter operated with 10 kW on 710 kHz, and the two shortwave transmitters were rated at 300 watts (for local coverage) and 1 kW (for external coverage). The 10 kW mediumwave KZFM was heard widely across the intervening saltwater pathway between Australia and New Zealand though the low powered shortwave units were seldom reported. It is known that the VOA facility in the Philippines did issue a few mediumwave QSLs (letters) to international radio monitors in Australia and New Zealand for the reception of their broadcasts over the interim KZFM mediumwave transmitter in Metro-Manila.
Even though it was American enterprise that constructed and operated VOA-OWI-KZFM, yet quite early it was recognized as owned by the Philippine government. It was on October 20, 1946 that the station was officially handed over to the Philippine government, yet it was still operated as an American station. It was at this stage that new studios were installed on the 4th floor of City Hall Building on Taft Avenue in Manila. When the American involvement finally ended, the station was located on Claro M. Recto Street, adjacent to the Far Eastern University.
In July 1947, an ITU (International Telecommunication Conference) in Atlantic City USA gave approval for the Philippine government to change their radio station designations from the K sequence to the D sequence. Eighteen months later, on January 1, 1949, all radio broadcasting stations throughout the Philippines abruptly made the change (much to the surprise of international radio monitors in Australia and New Zealand) and the PBS station KZFM became DZFM.
These days the callsign for the main PBS key network station in Manila was changed from DZFM to DZRB, simply because the two letters FM in a radio station callsign these days would seem to indicate an FM station, not mediumwave. PBS station DZRB in Manila is on the air with 60 kW on 738 kHz.
This feature was written by Adrian Peterson and originally aired on Adventist World Radio’s “Wavescan” DX program of February 27, 2022