Operating instructions

6 FIELD ALIGNMENT PROCEDURE

6.1 Standard Test Equipment

Some, or all of the following equipment will be required:

• AF signal generator, 75 - 3000Hz frequency range, with output level set to 387mV

RMS and, if the microphone input is to be tested, 10mV

rms output.

• Power supply set to 28Vdc, with current >10A.

• RF 50Ω load(s), 250W rated, return loss <-20dB, and total attenuation of 50dB

• Reference Clock. At least +6dBm output.

The external reference frequency is limited to:

500kHz, or any multiple,

any multiple of 128KHz greater than or equal to 512kHz,

any multiple of 160KHz greater than or equal to 480kHz

In Rev 4 or earlier revision systems, the external reference clock is limited to 10MHz.

In Rev 5 or later systems, the external reference clock can be as high as 24 MHz, and

can have an output level as low as 0dBm. The accuracy should be at least 0.5ppm,

preferably 0.1ppm

• RF Peak Deviation Meter

• True RMS AC voltmeter, and a DC voltmeter.

• RF Power Meter (accurate to 2%, i.e. 0.17dB)

• Some means of measuring Reverse Power, and a known 3:1 mismatched load.

6.2 Invoking the Calibration Procedure Manually

From Version 4 of the firmware, and version 1.4 of

WinTekHelp, the calibration

procedure can be performed through a Windows front end program. This is

documented in the WinTekHelp manual.

As well as the Windows based calibration procedure, the firmware still supports the

older command prompt method, which is described in this section.

The T50 has in-built firmware to perform calibration. This firmware requests the user

for information as to meter readings, and/or to attach or adjust an AF signal generator.

The firmware based calibration program can be accessed from a terminal, a terminal

emulator, or the WinTekHelp terminal emulator.

If the user selects the “Go to the Prompt Window” option from the main menu, they can

manually type commands to invoke the calibration procedure. When the exciter is

ready to accept commands it echoes the following prompt:

T50>

Via a terminal, or a terminal emulator, a user can type various commands in. The basic

command to start the calibration procedure is:

T50> cal

calibration_type

Where “

calibration_type” is one of:

a) misc: Miscellaneous parameters are defined and calibrated