turer is encouraged to use scale models to reduce cost and test time. If scale models are used, the buyer must review the design process and extent to which they are used and approve or waive any part of the manufacturer's standard full-size pattern test. "If the transmission line component of the system is greater than 300 feet in overall length or if the line will carry more than one RF signal, the line will be laid out in a single assembly and pressurized at twice the normal recommended level under operation in the field with dry air or nitrogen gas commonly used in the industry. The completed, pressurized assem- bly characteristic impedance will be optimized to a VSWR of 1.02:1 across an occupied bandwidth consisting of the television channel and any FM signals +/ - 0 Mhz above and below the bandwidth occupied by all the specified signals. The signal source and detection equipment will be described and noted with serial numbers, the name of the person making the measurements, their qualifications to do such work, and the dates the work was undertaken and completed with all interruptions in the daily routine noted. The line shall be terminated in a precision load of the same characteristic impedance as the line. The source and detec- tion equipment and load used shall be part of the manufacturer's normal test equipment and its calibration traceable to NBS standards commonly used for such purposes. "All tower top elbow complex units shall be built, optimized, and tested as a single unit. Upon completion of this process and prior to making ready for shipment, the manufacturer will notify the buyer of this fact and provide evidence that the unit has met or exceeded the agreed-upon specifications. The buyer will examine and approve the unit to be made ready to ship. "Factory RF Pulse and VSWR measurements must be made and recorded. These will be duplicated in the field. VSWR measurements must be made at intervals of .25 Mhz or less." DTV Transmitter Specification This specification covers commerical off-the-shelf 