Graham Brock, Inc.
Broadcast Technical Consultants
Vol. IX, No. 12
December 2002
The FCC has issued a Notice of Liability to a broadcaster in New Mexico for failing to comply with several conditions on its license. The station was inspected by the Commission and found to be operating with less than half its authorized power with an antenna height at variance with its authorization and, even at the operating power level, had a radio frequency radiation contribution level in excess of 300% of the allowable level. Based on the FCC notice, the potential fine for these matters could cost the licensee $28,000. The antenna is installed on a Forest Service Observation (Fire) tower and not secured from public access. The level of RF at the base of the tower exceeded the Commission’s limits.
The license for the station in question called for a specific antenna type and wavelength spacing. This was the basis for its initial grant. Many stations are required to specify a brand of antenna and, in some cases, the wave spacing of the antenna to limit downward radiation. If another model antenna is used, the replacement antenna must meet the same criteria and the model and type of the replacement antenna must be cleared by the Commission for RFR compliance. The type of antenna system used is even more critical at multi-user sites or on shorter towers, where the antenna is very low to the ground with high levels of emitted power.
The Commission was to have auctioned off spectrum in the same frequency band used by Satellite TV and would have allowed a multi-channel video distribution service. The auction was to be held in February 2003, but has been postponed until August. Several companies have filed Petitions for Reconsideration on MVDDS operations within this spectrum for fear of potential interference.
We were recently asked to assist in restoring service for a nearby FM station that had no backup transmitter and virtually no spare parts. The matter was further complicated by the fact that the transmitter manufacturer is no longer in business and there was no support available. After repairing the primary high voltage supply and a secondary power supply that presumably failed after an electrical surge, the transmitter had no apparent output power. With the right combinations, the transmitter appeared to be operating normally, but still no forward or reflected power. There was no excess heat in the cabinet. There was also no secondary power meter. While there is a history of failed power supply components and tube problems, there was no history of this type problem. It was finally determined that the switch that selects either the monitoring of forward or reflected power to the meter was damaged (in the forward power position). We replaced the switch and the output power registered. An alternative power meter would have helped diagnose this problem much faster. The failure of the switch was caused by general wear and tear, and not directly related to the power supply failure. Thanks for all of the input from area engineers who helped advise on this matter.
Happy Holidays!!!
The staff of Graham Brock would like to extend Holiday Greetings to you and hope that the New Year brings good health and prosperity. Our offices will be closed on December 25th, as well as January 1st.