783-6 Model High Power Constant Impedance Combiner

ERI FM filters and combiners have served the broadcast industry for over 40 years. The basic building block of ERI’s combiner and multiplexers system is a unique filter cavity. Only ERI offers a cylindrical cavity 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 assembly which maintains filter performance from a cold start to normal operating temperature without causing high transmitter VSWR. Only ERI filters incorporate a loop coupled design that allows more control over the filter pass band and offers performance superior to what can be achieved with the iris coupled cavities used by other manufacturers. ERI’s 780/783 constant impedance combiner module is modular in construction and is designed so that additional stations may be added in the future. The frequency of the additional station may be located anywhere within the FM broadcast band 0.8 MHz or more from any other system frequency.

To further enhance system reliability ERI FM filter systems do not include air filters that require replacement. In filter system designed to handle higher FM power levels the forced air cooling option uses a high reliability motorized fans that are mounted on each cavity and requires no additional floor space and does not require filtering. These band pass filters sets are available for protection from undesirable intermodulation products. They can also be configured to combine multiple FM channels in branch or constant impedance configurations.

Features and Benefits

• Cylindrical construction provides better mechanical and electrical stability than square or rectangular cavities
• 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
• ERI filters are loop coupled and fixed with bolted connections to couple cavities
• No Teflon or other insulating material used in the coupling between cavities,eliminating a primary point of failure, present in competitor’s designs.
• Loop coupling provides an adjustment (without disassembly) at the input and output of each cavity
• 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)

Specifications

Multiple Station Broad Port

Injected Station Port

Notes: (1) VSWR when terminated in 50-Ohm resistive load. (2) Loss values will be somewhat greater for frequency separations 2.0 MHz or less. (3) Group delay correction required for frequency separations 0.8 MHz or less and recommended for frequency separations of 2.0 MHz. or less. (4) 800 kHz or more removed from any signal appearing at the broad port. (5) Specifications presented are typical, total system performance may vary. In a continuing effort to improve products, ERI reserves the right to change specifications and features. (6) Dimensions do not include optional group delay compensation

All designs, specifications, and availabilites presented in this publication are subject to change without notice.