938-6 Series Constant Impedance FM Combiner Module

The ERI Model 783 Series Constant Impedance FM Combiner Modules provide stable high performance combining system for high power multi-station FM combining systems.


The ERI Model 938-6 is a low power constant impedance configuration utilizing two 938 Series, three section FM band pass filters with input and output 3 dB hybrids. The filters and hybrids use a high quality aluminum construction. The filter is floor mounted or can be suspended from the ceiling. The 938 Series is also available as a reflective filter. The 938-6 Series maintains a compact profile while maintaining high performance. The temperature compensated design is perfect for any low power FM Analog or IBOC application.

Features and Benefits

  • Floor standing compact constant impedance FM combiner module
  • Factory tuned to customer’s specified channel, yet can be easily field converted to any FM channel
  • Minor adjustments of cavity resonant frequency can be made during full power operation of filters
  • High stability temperature compensated cavities
  • Filter can be easily broken down for shipment and placement


  • Band:
  • Frequency Range:
    88 to 108 MHz
  • Number of Cavities:
    Three (3)
  • Power Handling:
    7 kW convection cooled
  • 14 kW with forced air cooling
  • Mounting Configuration:
    Floor Stand
  • Insertion Loss:
    < 0.4 dB at ±200 kHz
  • VSWR:
    < 1.1:1 at ±200 kHz
  • Group Delay:
    < 100 nsec overall variation ±150 kHz

Models Available

  • 938-6
    ERI Model 938-6 Constant Impedance FM Combiner Module, convection cooled
  • 938-6A
    ERI Model 938-6 Constant Impedance FM Combiner Module, with optional forced air cooling

Product Brochures

938-6 Constant Impedance FM Combiner Module Product Brochure

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