Operating instructions

This is the same mechanism that is used in 6.5 and 6.6. The user enters +, p, or P to

increase the Line 1 gain, to increase the deviation, or, -, m, or M to decrease the gain.

The user hits the Enter key when the desired deviation is set.

Now attach the audio signal generator to Line 2

Enter + or - to increase or decrease the deviation,

and <RET> when the deviation is 3kHz

Again the user enters +, p, or P to increase the Line 2 gain, or, -, m, or M to decrease the

gain. The user hits the Enter key when the desired deviation is set.

The firmware goes on to open the microphone audio path (note that the microphone

PTT switch does not need to be depressed for this). Note also that the application of a

10mV test input is a factory only test. An adequate test in field testing, would be to

speak into the microphone and see that the deviation meter responded accordingly.

Testing the microphone input.

Attach an audio signal generator to the microphone input.

Set the output to be a sine wave, 10mV rms and 1kHz.

Ensure that the deviation is between 2.7 and 3.3kHz

Enter <RET> when measurement complete.

Alert Engineering if there is a failure.

Then the Direct Audio input (with the low pass filter off) is tested.

Testing the Tone input.

Attach an audio signal generator to the Tone input.

Set the output to be a sine wave, 129mV rms, and 1kHz.

Enter + or - to increase or decrease the deviation,

and <RET> when the deviation is 1kHz

And then user then follows the same procedure as defined for setting the Line 1 and

Line 2 gains.

6.2.6 The “Power” Calibration Procedure

T50> cal pwr

All Power Amplifiers are calibrated ex-factory. All the important parameters, such as

the forward and reverse power sense adjustment, and drain bias settings are not

dependent on the exciter, and thus any factory calibrated PA50 power amplifier can be

connected to, and work correctly with any T50 exciter. The frequency range of the

amplifier is defined by three jumper settings on the external PA, which the CPU can

detect. Thus the CPU knows (on power up) what frequencies are, or are not, possible to

be used with the PA.

The exciter may store some PA specific parameters, such as the Serial Number of the

PA, and also some offset values for the pre-amp drain current, and the output stage

drain current. These latter offsets improve the accuracy of the over current alarm

testing, (but are not strictly necessary). In order to set these parameters, it is advised

that this procedure be performed every time an exciter is used with a new External

Power Amplifier. Note that many of the stages can be skipped if they have been

performed before.

The program begins: