780-8 Series Constant Impedance FM Combiners Series Constant Impedance FM Combiners ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output (convection cooled) Model:

780-8 Series Constant Impedance FM Combiners

Features• Cylindrical construction

provides better mechanical andelectrical stability than squareor rectangular cavities

• Factory tuned to customer’sspecified channel, yet can beeasily field converted to anyFM channel

• Minor adjustments of cavityresonant frequency can bemade during full poweroperation of filters

• High stability temperaturecompensated cavities

• ERI filters are loop coupledand fixed with boltedconnections to couple cavities

• No Teflon or other insulatingmaterial used in the couplingbetween cavities, eliminating aprimary point of failure, present in competitor’s designs.

• Loop coupling provides an adjustment (without disassembly) at the input and output of eachcavity

• Marman clamp connection allows close cavity placement• Ability to change frequency quickly and with a minimum of disassembly• Filter can be easily broken down for shipment and placement• Temperature indicator provided on all filter sets• Optional non-adjacent coupling and group delay compensation available• Easily assembled floor standing units (hardware for ceiling suspension available on request)

ERI FM filters and combiners have served the broadcast industry for over 40 years. The basic buildingblock of ERI’s combiner and multiplexers system is a unique filter cavity. Only ERI offers a cylindricalcavity and all internal components in the RF path are silver plated. The result is an extremely efficient(low loss) and stable filter. ERI filters include a unique bellows temperature compensation assemblywhich maintains filter performance from a cold start to normal operating temperature without causing hightransmitter VSWR. Only ERI filters incorporate a loop coupled design that allows more control over thefilter pass band and offers performance superior to what can be achieved with the iris coupled cavitiesused by other manufacturers. The use of cylindrical tanks provides the benefit of a mechanically rigidtank design. ERI’s 780-8 constant impedance combiner module is modular in construction and isdesigned so that additional stations may be added in the future. The frequency of the additional stationmay be located anywhere within the FM broadcast band 0.8 MHz or more from any other systemfrequency.

The filter system offered is configured in a floor mounted configuration to maximize heat transfer, powerhandling capability, and simplify system modification in the future. The individual modules can beoptionally forced air cooled, for higher power handling capability. There are also optional configurationsthat include ceiling hung frames and floor stands to accommodate a wide variety of physical spacerequirements. The combiner module can also be equipped with circulators for the dump load ports of thesystem to enable the capability or “reverse feeding” the combiner with the digital IBOC FM signals.


780-8 Series Constant Impedance Combiner Specifications:Model: 780-8Combiner Type: Band Pass Constant ImpedanceVSWR: 1.1:1 ±200kHz, maximumInjected Port to Broad Port Isolation: ≥-30 dB Injected Port to Injected Port Isolation: ≥-55 dB, with two or more modules Output Connector: 3-1/8-inch, 4-1/16-inch, or 6-1/8-inch EIA, 50 ohmsOutput Power Capability: 140 kW capability (limited by line size)Combiner Module Size and Weight:

Convection cooled model:3-1/8-inch Output

Height: 48 in 122 cmWidth: 46 in 117 cmLength: 112 in 284 cmWeight: 840 lbm 381 kg

With forced air cooling:Height: 56 in 142 cmWidth: 46 in 117 cmLength: 112 in 284 cmWeight: 1000 lbm 454 kg

Convection cooled model:6-1/8-inch Output


With forced air cooling:Height: 56 in 142 cmWidth: 46 in 117 cmLength: 112 in 284 cmWeight: 1110 lbm 503 kg

AC power required for forced air cooling: 115 VAC 4 ampsGroup Delay Compensation Module Size and Weight:


Multiple Station Broad Port:Frequency: All FM Broadcast Channels (88 to 108MHz)Connector: 3-1/8-inch, 4-1/16-inch, or 6-1/8-inch EIA, 50 ohmsVSWR

1: <1.06:1

Insertion Loss2: -0.05dB Typical

Group Delay3: <75ns Overall Variation, Carrier ± 150kHz

Injected Station Port Performance:Frequency

4: All FM Broadcast Channels (88 to 108MHz)

Power Rating: 39 kWConnector: 3-1/8-inch 50-Ohm EIA (flanged)VSWR

1: <1.06:1 at ±150 kHz

Insertion Loss2: <0.45 dB without GDC Module

<0.70 dB with GDC ModuleGroup Delay

3: <75 nsec overall variation ±150 kHz

<25 nsec overall variation ±150 kHz with optionalGroup Delay Compensation

1) When terminated in 50-Ohm resistive load.2) Loss values will be somewhat greater for frequency separations less than 2.0 MHz.3) Group delay correction required for frequency separations less than 2.0 MHz.4) 800 kHz or more removed from any signal appearing at the broad port.


ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output (convection cooled)

Model:

Height: 48 in 122 cmWidth: 46 in 117 cm

Length: 112 in 284 cmWeight: 840 lbm 381 kg

780-8 (3-1/8-inch output)


ERI Model 780-8 Constant Impedance FM Combiner Module, 6-1/8-inch output (convection cooled)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output, with optional highlevel group delay compensation (convection cooled)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 6-1/8-inch output, with optional highlevel group delay compensation (convection cooled)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output (forced air cooling)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 6-1/8-inch output (forced air cooling)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output, with optional highlevel group delay compensation (forced air cooling)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 6-1/8-inch output, with optional highlevel group delay compensation (forced air cooling)

Model:





ERI Model 780 High Level Group Delay Compensation Module

Model:



780 Group Delay Module


ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output, mounted inoptional floor stand (convection cooled)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 6-1/8-inch output, mounted inoptional floor stand (convection cooled)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output, mounted inoptional floor stand (forced air cooling)

Model:





ERI Model 780-8 Constant Impedance FM Combiner Module, 6-1/8-inch output, mounted inoptional floor stand (forced air cooling)

Model:




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780-8 Series Constant Impedance FM Combiners Series Constant Impedance FM Combiners ERI Model 780-8 Constant Impedance FM Combiner Module, 3-1/8-inch output (convection cooled) Model: