_New Digital RF Ammeter Systems _New

FEATURES 100:1 Current Range 3-1/2 Digit Display 2% Accuracy Autoranging Modulation Independent Wide Frequency and Temperature Ranges Dual 2.15 VDC/10 VDC Full Scale Remote Outputs

Introduction

The Model DTCA Digital RF Ammeter provides AM broadcasters and other high power RF operators with an accurate, reliable and high resolution digital instrument for measuring RF current.

The 100:1 dynamic operating range enables RF current measurement over a 10,000:1 power range and allows the broadcaster to use a single instrument for day, night, pre-sunrise and post-sunset operating modes. The ammeter system uses the Model TCT toroidal current transformer to provide a sample voltage proportional to the RF current. The ammeter converts this RF voltage to a DC voltage which is applied to a 3-1/2 digit display. The reflective liquid-crystal display with 0.7 inch character height provides a high resolution and easily readable RF current magnitude indication. Over the AM broadcast band, the DTCA provides an accuracy of better than 2% with a resolution better than 1/100 of the RF current. The DTCA indicates the average RMS current independent of amplitude or phase modulation. The dual remote outputs of 2.15 VDC full scale and 10.0 VDC full scale easily interface with existing remote monitoring equipment.

The DTCA circuit design is inherently wide band to extend RF current measurement capabilities for LF applications at frequencies as low as 20 kHz and for HF applications at frequencies up to 5 MHz. The DTCA circuit is temperature compensated to enable rated accuracy performance over a -40°C to +50°C temperature range.

Model DTCA-10 Digital RF Ammeter

Description

The digital RF Ammeter series encompasses several models to provide RF current measurement over the range from 0.1 to 160 Amperes full scale. The 100:1 dynamic operating range enables RF current measurement over a 10,000:1 power range. Since the ammeter indicates the average RMS current independent of modulation, it is practical to use the ammeter up to the full scale value.

The standard interconnecting coaxial cable length is six feet. Longer coaxial cable lengths and double shielded coaxial cable are optionally available for any DTCA system for high RF field conditions and for RF radiation exposure reduction.

Ammeter Accuracy and Calibration

The Digital RF Ammeter Systems are capable of measuring RF current with excellent accuracy. The accuracy specification of 2% of reading is guaranteed over a temperature range of ­40°C (­40°F) to +50°C (+122°F) and over a frequency range of 500 kHz to 2000 kHz.

Every Digital RF Ammeter is calibrated at a frequency of 1 MHz at the Delta laboratory. The flat frequency response and compensated temperature characteristics of the ammeter assure accurate current measurement. The calibration of the ammeter is warranted for a period of one year under normal use conditions. Excluding damage due to lightning, Delta will recheck the calibration and make repairs, if necessary, without charge during this period. These services are available at a nominal charge at any time thereafter.

Model DTCA-10-HV Digital RF Ammeter

Meter Nomenclature

The DTCA Digital RF Ammeter series includes a wide variety of operating current ranges and current transformer conductor voltage ratings which are uniquely defined in the model designation system. Standard current ranges are 0.1 to 10A, 0.2 to 20A, 0.4 to 40A, 0.8 to 80A and 1.6 to 160A. Each of these five current ranges are available with current transformer conductor voltage ratings of 10 kV, 20 kV and 42.4 kV.

DTCA-N: The standard series is supplied with a current transformer rated for operation at conductor voltages as high as 14 kV peak (10 kV_RMS). The transformer provides a 1.25" diameter clearance hole for the antenna connector. A 0.38" to 0.5" diameter tubular conductor contained in the clearance hole provides optional voltage capability. The TCA-LS-8 and TCA-LS-11 line sections which increase the voltage rating by approximately 50% are available as a factory installed option.

DTCA-N-HV: The suffix "HV" appended to any of the DTCA series model numbers specifies that the current transformer supplied with the meter is the high voltage type rated for operation at conductor voltages as high as 28 kV peak (20 kV_RMS). The transformer provides a 3.38" diameter clearance hole for the antenna conductor. A 0.75 to 1.0" diameter tubular conductor centered in the clearance hole provides maximum voltage capability. Corona rings which increase the voltage rating by approximately 5% are available as a factory installed option.

DTCA-N-XHV: The suffix "XHV" appended to any of the DTCA series model numbers specifies that the current transformer supplied with the meter is the extra high voltage type rated for operation at conductor voltages as high as 60 kV peak (42.4 kV_RMS). The transformer provides a 6.0" diameter clearance hole for the antenna conductor. A 2.0 to 2.25" diameter tubular conductor centered in the clearance hole provides maximum voltage capability.

Model DTCA-10-XHV Digital RF Ammeter

SPECIFICATIONS

Frequency Range: 0.5 to 2 MHz at rated 2% accuracy, 20 kHz to 5 MHz with 5% accuracy Operating Range: 100:1 Standard RF Current Ranges: DTCA-10: 0.1 to 10 A DTCA-20: 0.2 to 20 A DTCA-40: 0.4 to 40 A DTCA-80: 0.8 to 80 A DTCA-160: 1.6 to 160 A Indicating Instrument: 3 1/2 digit/2000 count reflective LCD display with 0.7 inch (17.8 mm) character height Accuracy: Better than 2% of reading. Accuracy may be reduced if RF currents induced by other stations are 5% or greater than the current to be measured. Resolution: One part in 100 minimum, one part in 1200 maximum Remote Outputs: 1) 2.15 VDC full scale, 16K source compatible with Delta Model TCA-IBA Buffer amplifier, output linear with RF current 2) 10.0 VDC full scale, 16K source, output linear with RF current Power Requirement: 120/240 VAC primary/18 VAC @ 200mA secondary power module (supplied) or 18 to 28 VDC, 80 mA power supply (TCA-PS2 or equivalent) Range Selection: Automatic Current Transformer: Delta Model TCT, TCT-HV or TCT-XHV for AM broadcast band (500 kHz to 2 MHz); Suitable transformer required for lower/higher frequencies Interconnecting Cables: Standard six foot, 50 Ohm coaxial cable supplied to connect transformer unit to detector/display unit. Longer cable length and double shielded coaxial cable are optionally available. Conductor Voltage to Ground (RMS Equivalent of Peak Modulation Voltage): DTCA-N Series: 10 kVRMS DTCA-N-HV Series: 20 kVRMS DTCA-N-XHV Series: 42.4 kVRMS Temperature Range: -40°C (-40°F) to +50°C (+122°F) Modulation Characteristics: Indicates average RMS current with minimum modulation effect. Will indicate carrier shift.

Users of Delta's Model TCA RF Ammeter System may easily upgrade to the Model DTCA Digital RF Ammeter System. The digital ammeter is interchangeable with the TCA ammeter for both RF input and remote DC output. Please contact the factory to arrange return of your TCT unit for calibration with the DTCA Digital RF Ammeter.