TELEWAVE 44L1P (01) PDF DOCUMENT

The specifications for the TELEWAVE 44L1P are as follows:

The TELEWAVE 44L1P Broadband RF Wattmeter includes the following features:

• Displays five power ranges

• Measures 1 to 500 watts

• Does not require inserts

• Does not require band switching

• Fully operable in freezing conditions

• Provides 5 watts full scale range

• Interchangeable connectors (QC)

• Lightweight, rugged and easy to carry

• -40 dB RF sampling port (Model 44L1P)

Follow this procedure to prepare for an RF power measurement with the TELEWAVE 44L1P:

Step 1: Remove the RF power from the transmission line.

Step 2: Set the RF Range Switch to the 500 Watt position.

Step 3: Connect the RF Source to the Model 44L1P FWD input connector, located on the left side of the instrument nearest the mode switch.

Step 4: Connect the RF Load to the Model 44L1P FWD output connector, located on the right side of the instrument nearest the range switch.

To make an incident or forward power measurement with the TELEWAVE 44L1P, follow these steps:

Step 1: Set the Mode Switch to the FWD position.

Step 2: Apply RF power to the transmission line.

Step 3: Move the RF Range Switch to a lower range if necessary to obtain a reading in the upper third of the scale.

Step 4: Note the meter reading.

To make a reflected or reverse power measurement with the TELEWAVE 44L1P, follow these steps:

Step 1: Set the Mode Switch to the REV position.

Step 2: Apply RF power to the transmission line.

Step 3: Move the RF Range Switch to a lower range if necessary to obtain a reading in the upper third of the scale and note the reading.

Follow this procedure to determine the Voltage Standing Wave Ratio (VSWR):

Step 1: Perform the procedures for measuring forward and reflected power. Record the true incident and reflected power.

Step 2: Refer to the VSWR Chart on the rear of the instrument. Apply the readings from Step 1 to the chart.

Step 3: The VSWR is read from the nearest sloping line. For higher accuracy, calculate the VSWR by the formula:

VSWR = (1 + √(P_REV / P_FWD)) / (1 – √(P_REV / P_FWD))

Where P_REV is the reflected power in Watts and P_FWD is the forward power in Watts.

Use the following procedure to determine the actual power delivered to the load:

Step 1: Perform the procedures for measuring forward and reflected power. Record the true incident and reflected power.

Step 2: Subtract the reflected power from the incident power. This difference is the true power at the load.

Directivity Error:

Directivity error results from the effect of imperfect directivity in the Dual Directional Coupler. Directivity is the ability of the coupler to sense power flowing in one direction and be insensitive to any power which may be flowing in the reverse direction. The directivity error is included within the specified instrument accuracy.

Insertion Error:

When the RF load and RF source are well matched, any error contributed by inserting the TELEWAVE 44L1P Wattmeter alone is negligible. However, the use of a jumper cable to connect the wattmeter in the system will change the characteristic impedance of the line, especially in a system with high VSWR. Since the impedance on either side of 1/2 wavelength is identical, the jumper cable added to the input or output of the wattmeter should be of an appropriate length to equal 1/2 wavelength at the frequency of operation, thus eliminating any error due to the additional length.

Before beginning, remove the four bumper screws from the rear panel to access the adjustment potentiometers.

Forward Mode Adjustment Procedure:

Step 1a: Set the RF source to 100 MHz.

Step 1b: Set the wattmeter Mode Switch to FWD position.

Step 1c: Set the wattmeter RF Range Switch to the 5 watt range.

Step 1d: Set the RF source to 4 watts output.

Step 1e: Adjust R1 until the TELEWAVE 44L1P wattmeter reads 4 watts.

Step 2a: Set the wattmeter RF Range Switch to the 15 watt scale.

Step 2b: Set the RF source to produce 11 watts output.

Step 2c: Adjust R3 until the TELEWAVE 44L1P wattmeter reads 11 watts.

Step 3a: Set the wattmeter RF Range Switch to the 50 watt scale.

Step 3b: Set the RF source to produce 35 watts output.

Step 3c: Adjust R7 until the TELEWAVE 44L1P wattmeter reads 35 watts.

Step 4a: Set the wattmeter RF Range Switch to the 150 watt scale.

Step 4b: Set the RF source to produce 105 watts output.

Step 4c: Adjust R11 until the TELEWAVE 44L1P wattmeter reads 105 watts.

Step 5a: Set the wattmeter RF Range Switch to the 500 watt scale.

Step 5b: Set the RF source to produce 325 watts output.

Step 5c: Adjust R15 until the TELEWAVE 44L1P wattmeter reads 325 watts.

Reverse Mode Adjustment Procedure:

Step 6a: Disable the RF source output.

Step 6b: Set the wattmeter Mode Switch to REV position.

Step 6c: Reverse the wattmeter RF connections in the RF line.

Step 6d: Repeat Steps 1c through 5c for the 5, 15, 50, 150 and 500 watt ranges, using adjustment points R2, R6, R10, R14, and R18.

Step 6e: Reinstall the rear panel and bumper screws.

The following chart shows lengths for a 50-ohm, RG-213 jumper cable, including N connectors, to minimize potential measurement errors in systems with high VSWR. The jumper cable and wattmeter together should equal as close to 1/2 wavelength equivalent as possible at the test frequency.