Labgear CM 7281 Installation Instructions

CM 7281 VHF-UHF single input 

CM 7282 VHF-UHF dual Input 

MATV Distribution Amplifiers 

Introduction and Applications 

These fully screened amplifiers are ideal for handling TV and FM DAB radio signals in small and medium 

sized MATV distribution systems. These amplifiers have a single output and are used in conjunction 

with a passive distribution network built using splitters and taps (also available from Labgear). Advice on 

the design of suitable distribution networks is available from Labgear's technical support department if 

required. 

CM 7281 

This is a single-input wideband amplifier covering Bands I to V (40-862 MHz). It should be used 

where the signals from VHF and UHF antennas have been combined before reaching the amplifier. 

CM 7282 

This type has separate VHF and UHF inputs, each with its own gain control. Separate feeds from the 

antennas are required, but the ability to set VHF and UHF signal levels separately is an advantage. The 

VHF operating frequency range of the CM 7282 has been configured for use in Bands I to 111(40-300 

MHz). 

Digital applications 

Both units are suitable for handling digital terrestrial TV (DTT) signals in addition to the analogue services. 

Distribution of DTT signals requires careful attention to system design and to signal levels for 

satisfactory results. 

Using a UHF pre-amplifier 

In weak UHF signal areas, or where a long downlead cable run is required, it may be desirable to use a 

masthead preamplifier mounted close to the UHF antenna. These MATV amplifiers feature built-in 

12V input line-powering; there is no need to use a separate power unit for the masthead amplifier.-- 

(Type CM 7282 has line-power on the UHF input only.) 

The built-in line-power is rated at 40mA (fully short-circuit proof) and is compatible with the majority 

of Labgear masthead preamplifiers. 

Installation Instructions 

The preamplifier gain used should be kept to a minimum and generally only needs to exceed the 

down lead cable loss by about 6dB. A single-stage 15dB gain masthead (PUM111) will be suitable for 

the great majority of applications. Use of excessive amounts of gain will lead to severe cross-

modulation and intermodulation problems.