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8 <br /> 7. Transmitters in the 512 to 746 Mhz range shall have a band pass filter providing a minimum <br /> of 20 dB of attenuation 2.0 Mhz removed from the operating frequency. Transmitters in this <br /> frequency range shall also be fitted with dual isolators providing a minimum of 50 dB isolation. <br /> 8. No broadcast transmitters in the 746 to 806 Mhz range shall be permitted in SERS facilities. <br /> 9. Transmitters in the 806 to 990 Mhz range shall have a band pass filter providing a minimum <br /> of 15 dB of attenuation 3.0 Mhz removed from the operating frequency. Transmitters in this <br /> frequency range shall also be fitted with dual isolators providing a minimum of 50 dB isolation. <br /> Window filtering with broader responses may be authorized on a case by case basis. <br /> 10. Transmitters in the 1500-2000 Mhz range shall have a band pass filter providing a minimum <br /> of 15 dB of attenuation 3.0 Mhz removed from the operating frequency. Transmitters in this <br /> frequency range shall also be fitted with dual isolators providing a minimum of 50 dB isolation. <br /> Window filtering with broader responses may be authorized on a case by case basis. <br /> Site Engineering Standards and Site User Practices <br /> The following site engineering standards and site user practices shall be observed: <br /> 1. A band pass cavity shall always be used before each receiver. A window filter may be <br /> substituted in multicoupled systems. Crystal filters are also advisable at crowded facilities. <br /> 2. A band reject duplexer may not be used unless accompanied by the required band pass <br /> cavities. A pass reject duplexer may be used, provided the duplexer band pass characteristics <br /> meet the minimum requirements for transmitter band pass filtering. <br /> 3. All cables used must, at minimum, be double-shielded with 100%braid coverage. Use of <br /> solid outer shield cables (i.e. 'Heliax') is strongly encouraged. All external feed lines shall be <br /> solid-shielded. <br /> 4. All cables used shall be covered with an insulating jacket. Cables used externally shall be <br /> covered with an ultra-violet resistant insulating jacket. No cables with aluminum outer <br /> conductors shall be used. <br /> 5. Use of constant impedance connectors shall be required. Type 'N,' BNC or 7/16 DIN <br /> connector types are typical constant impedance connectors. Adapters shall not be used for <br /> permanent connections. <br /> 6. All equipment shall be properly grounded. Grounding shall be performed by grounding the <br /> radio equipment manufacturers designated equipment ground and shall be tied to the radio <br /> facility equipment ground,preferably using flat copper strap or copper braid. The AC line <br /> ground shall also be used to provide the protective ground. Use of three-wire to two-wire <br /> adapters shall be prohibited. The facility manager shall identify the radio facility ground point. <br /> 75 <br /> 27 <br />