Section 2: Installation
NetClock/GTP Instruction Manual
Page 2-3
2.2.1 Cable
Lengths
Using Spectracom CA07xxx or Belden 8267 coax, the maximum antenna cable length
permitted is 200 feet. These cables attenuate the GPS signal by 10 dB per 100 feet of
coax. Installations requiring longer antenna cables may use the Model 8227 Inline
Amplifier, or lower loss cable. Refer to Section 2.5 for additional information on the
Model 8227.
When selecting alternate antenna cable sources, the attenuation characteristics at the
GPS frequency of 1575.42 MHz must be known. To ensure optimum receiver
performance, the total antenna cable attenuation must not exceed
20 dB. Cable attenuation of greater than 20 dB requires the use of a Model 8227 Inline
Amplifier.
2.3
MODEL 8226 IMPULSE SUPPRESSOR
Spectracom recommends the use of an inline coaxial protector for all products with an
outside antenna. Spectracom offers the Model 8226, Impulse Suppressor, to protect
the receiver from damaging voltages occurring on the antenna coax. Voltages
exceeding the impulse suppresser trip point are shunted to the system ground. The
Model 8226 is designed to withstand multiple surges.
Mount the suppressor indoors, preferably where the coax enters the building. Install the
suppressor on a grounding panel or bulkhead using the BF adapter bracket
(Spectracom part # MP10-0000-0002) as shown in Figure 2-2.
PART #: MP10-0000-0002
INSTALL RUBBER
WASHER
FIGURE 2-2 MODEL 8226 IMPULSE SUPPRESSOR
Refer to Section 2.4 for additional information on the copper grounding panel (part #
MP10-0000-0001) offered by Spectracom.
