TB7300 Installation and Operation Manual Installation 73
© Tait International Limited December 2022
5.7.5 Connecting an External Frequency Reference
An external reference frequency is not normally required for B band.
However, an external reference can be used when you need to maximize
the range of the base station. The external reference frequency can be
10MHz or 12.8MHz, with an input level of 300mV
pp
to 5V
pp
. The
stability of this reference should be better than 100 parts per billion. The
base station automatically detects the frequency of the external reference
and configures itself accordingly.
Notice An external reference is required for simulcast operation.
If an external reference is required, enable the external reference “external
reference absent” alarm (Configure > Alarms > Control).
Use a 50Ω coaxial cable (RG58 or RG223) to connect the external
reference to the base station’s external reference frequency input. You can
daisy-chain up to eight base stations using BNC goal post adaptors (see
Figure 5.7). The maximum overall cable length is 30m. Terminate the last
connection (including single base stations) with a 50Ω load.
Figure 5.7 BNC goal post adaptor (part number 240-06913-00)
Figure 5.6 Daisy-chaining an external frequency reference input
maximum of eight base
station loads on one
frequency reference output
maximum overall cable
length is 30m
50Ω termination
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