User's Manual

94 Installation TB9300 Installation and Operation Manual
© Tait Limited June 2016
5.6.6 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. For K4 band, the internal frequency reference
accuracy is inadequate, and an external reference must be used. 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 reciter automatically detects the frequency
of the external reference and configures itself accordingly.
If an external reference is required, enable the 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 F-junctions. The maximum
overall cable length is 30m. Terminate the last connection (including single
base stations) with a 50Ω load.
Figure 5.11 Daisy-chaining an external frequency reference input
50Ω termination
(also needed for
single base stations)
maximum of eight base
station loads on one
frequency reference output
maximum overall cable
length is 30m