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CA2P600B Series
Balanced FM Combiners

Rev : 02 | Rev date : 16 Nov 2021

RFS offers a comprehensive range of FM combiners to suit all common FM combining applications. The balanced, or constant impedance, bandpass design provides the best possible frequency response and specifications, and is ideal for large multi-station channel comnbiners or when frequency spacings are very close.


A balanced module consists of a balanced pair of bandpass filters, two 3dB couplers and a balancing load. The narrowband input corresponds to the filter resonant frequency, whereas the wideband input can be any other frequency in the 87.5 - 108 MHz band. The wideband input signal loss is very low because it does not pass through the bandpass filters. Modules can therefore be cascaded to form a multichannel combiner. The module design enables extra channels to be easily added at a future date.



  • Compact size with small footprint for design power rating
  • Can be field retuned to any frequency in the 87.5 - 108MHz band
  • Invar temperature compensation for stable operation
  • Vertical entry and exit without additional elbows
  • Natural convection cooling
  • Group delay corrector modules are available for complex multichannel systems
  • Custom options with U-Links, motorised switches, monitoring systems, etc. are available

Balanced FM Combiner with 2 Pole 600mm Filters

Technical features


Product LineCombiner Radio
Product TypeBand II (VHF) FM Balanced Combiner
Filter Type and Size2 Pole, 600mm

Electrical Specifications

Frequency RangeMHz87.5 - 108
Impedance Ω50
Minimum Channel SpacingMHz1.6
Narrowband Input PowerkW

30 (Temp Rise: 30°C)

Narrowband Insertion LossdB<0.2
Amplitude VariationdB< 0.1 to ±120 kHz
Group Delayns< 40 to ±100 kHz
Wideband Input Insertion Loss dB<0.1
Return Loss dB>30
Isolation - N/B to W/BdB>32
Isolation - W/B to N/BdB>50
Input Connector3-1/8" EIA (unflanged female) (Note 1)3-1/8" EIA (unflanged female) (Note 1)
Wideband Input Connector3-1/8" EIA (unflanged female) (Note 1)6-1/8" EIA (unflanged female) (Note 1)
Output Connector3-1/8" EIA (unflanged female) (Note 1)6-1/8" EIA (unflanged female) (Note 1)
Maximum Output PowerkW50160

Mechanical Specifications

Weightkg (lb)216 (476)250 (551)
Dimensions (Height or Length) cm (in)151 (59)160 (63)
Dimensions (Width) cm (in)121 (48)121 (48)
Dimensions (Depth) cm (in)150 (59)150 (59)
CoolingNatural convection

Temperature Specifications

Maximum Operating Temperature °C (°F)80 (176)
Ambient Temperature Range °C (°F)-5 to 55 (23 to 131)
Maximum Temperature Rise °C (°F)30 (86)
Humidity%95, non-condensing



Combiner Module Configuration

External Document Links


  • Note 1. Other connectors are available on request