Portable Bypass Unit 3-Channel 835-849 MHz Microwave Receiver JFW 50R-083 LNA

Portable Bypass Unit 3-Channel 835-849 MHz Microwave Receiver JFW 50R-083 LNA

This is a custom-built portable 3-channel microwave bypass receiver designed to operate in the 835–849 MHz cellular band. Housed in a rugged aluminum flight case with carry handle and locking latches, the unit provides three independent receive channels — labeled Alpha, Beta, and Gamma — each with its own SMA input and SMA output on opposite panels. Power is supplied via a 24 VDC input on the front panel, protected by a 3A fuse, with a dedicated Bypass Power On switch and chassis ground terminal.

Specifications & What's Included

• Frequency range: 835–849 MHz (cellular AMPS/downlink band)
• Number of channels: 3 independent (Alpha, Beta, Gamma)
• Each channel contains: sharp bandpass filter, duplex filter receiver section, circulator, 17 dB low noise amplifier (LNA), second circulator, second amplifier stage, third circulator, and variable step attenuator
• Attenuator range: 0–10 dB in 1 dB steps per channel (front-panel rotary knob)
• Attenuators: 3x JFW Industries Model 50R-083 coaxial step attenuators (Indianapolis, IN, USA)
• Coaxial isolators: 9x Channel Microwave Corporation Model AU323-5
• RF filter: ZoMatch BCCD842N-A02 (835–849 MHz)
• LNA assembly P/N 203002-001 — gain: 17.2 dB (per internal label)
• Assembly P/N 201250-134 (WO# 500757)
• Input connectors: 3x SMA (Alpha, Beta, Gamma — one panel)
• Output connectors: 3x SMA (Alpha, Beta, Gamma — opposite panel)
• Power input: 24 VDC
• Fuse: 3A
• Form factor: portable aluminum flight case with carry handle and latches

Applications

This type of portable microwave bypass receiver was used in cellular RF engineering, network testing, and signal monitoring applications in the 835–849 MHz AMPS (Advanced Mobile Phone System) downlink band — the frequency range used by first-generation analog cellular networks in North America and some second-generation (GSM/CDMA) deployments. A bypass receiver of this architecture — combining sharp bandpass filtering, low-noise amplification, circulators for signal isolation, and calibrated step attenuation — allowed engineers to tap, monitor, or route RF signals from a base station or distributed antenna system (DAS) without significantly disrupting the main signal path. The three-channel design (Alpha, Beta, Gamma) supports simultaneous monitoring of multiple sectors or signal paths from a single portable unit. The self-contained flight-case enclosure made it suitable for field deployment at cell sites, in RF labs, or in drive-test and network optimization scenarios. Units of this type were common tools for RF engineers working on AMPS and early CDMA/GSM infrastructure throughout the 1990s and into the 2000s. They remain of interest today for legacy network maintenance, RF research, spectrum monitoring, and custom receiver projects in the 800 MHz band.