The Delta Electronics CPB-1A Common Point Impedance Bridge is an operating impedance bridge designed for permanent installation in the phasing equipment at the antenna common point. The CPB-1A operates with common point power up to 50 kW with 100% amplitude modulation on a continuous basis. It features two 4" dials calibrated directly in resistance and reactance. A front panel meter operates as a null detector. The R and X dials are manipulated as a normal bridge to give a null indication on the panel meter while the transmitter is operating at full or reduced power. The value of the common point resistance and reactance are then read directly from the two dials.
Many directional antennas have common point impedances that vary from time to time due to seasonal drift of the antenna parameters. The Common Point Bridge permits the station operator to determine the common point impedance at all times, even during normal operating hours. By minor adjustment of the common point resistance control, the station can maintain radiated power at the full license value at all times. Changes in the antenna system that affect the common point impedance are easily detected with the Common Point Bridge.
This version of the CPB-1A is mounted on a standard 7" high by 19" wide equipment rack mounting panel.
The CPB-1A may be supplied with a Delta TCA RF Ammeter System factory installed. The complete series of 5, 10, 20, 40, 80 and 160 Ampere single scale and dual scale RF Ammeters with appropriate sampling transformer are available. With the RF Ammeter mounted on the bridge panel, the total RF power is easily determined from the load current and measured resistance.
• Frequency Range: 500 kHz to 1.65 MHz
• Power Rating (at 100% amplitude modulation continuous): 50 kW
• Resistance Range: 30 to 100 ohms
• Reactance Range: ±50 ohms at 1 MHz
• Accuracy: Resistance: ±2% ±1 ohm; Reactance: ±2% ±1 ohm (Provision is made for your consultant to adjust the calibration to agree exactly with your licensed resistance value)
• RF Source: Transmitter operating at normal or reduced power acts as source, no generator is required
• Detector: Tuned internal detector with 25 µA panel meter; BNC output connector for use with external detector
• Terminals: 1/2" Copper Straps
• Mounting: Standard 7" high x 19" wide equipment rack panel
• Dimensions: 7" high x 19" wide x 10" deep
