QRF QRBA Quality Rack Isolated Amplifier

The QRBA is our second generation of isolation amplifiers for headend combining use. The 3.5-inch rack mount chassis comes with up to five well-shielded circuit boards with bandwidths up to 870 MHz.

Each of the independent RF amplifiers utilizes a single hybrid with impedance match to a built-in 15 dB directional coupler assembly (optional 10 dB coupler available upon request). Mounting the coupler after the hybrid inside the amplifier chassis reduces the number of cables and outboard directional couplers in the headend cable lash-up. Each amplifier also has a forward facing RF output test point calibrated at -30 dB. The input equalizer and pads are accessed via the front cover. All RF connections are rear facing and easily accessed from the front of the rack due to the shallow depth of the chassis. Each hybrid has a separate heat sink for optimum cooling.

The QRBA is used as the last amplifier before feeding the trunk or laser outputs from the headend. Franchise or node-specific channels of video or digital signals may be reused in many different areas of the cable system. QRBA prevents signal feedback that can cause co-channel interference with similar channels on the same frequencies fed to other trunks or fiber nodes. This allows clear local access channels, customized advertising insertion channels, RF modems and telco signals to be sent to targeted franchise areas.

QRBA also uses 17 and 21 dB push-pull hybrids. QRBA power-doubled units allow only 2 or 3 amplifiers per chassis using 19 or 22 dB power-doubled hybrids.