The "Deviation" Calibration Procedure - RF Technology Eclipse Series Operation And Maintenance Manual

6 FIELD ALIGNMENT PROCEDURE
The user may see the following error message.
The Model Name is T50
and the Serial Number is 002313
Please take note of the Model, DAC values, serial number and
crystal temperature, and report this problem to RFT Engineering.
If this message is seen, it indicates a potential fault condition. If the final text indicates
that the channel and mod reference errors are within specification (the last text output),
then the unit is able to be used, but nonetheless, it is advisable that an e-mail be sent to
RF Technology indicating the problem. Such a problem may be caused by a crystal
having aged to such an extent, that it is getting close to the region where it may soon, no
longer be adjusted, or that, with further degradation, the low frequency performance
may be compromised.
As no other calibration procedure requires the top cover to be removed, you should
replace the cover, should you have had to remove it for this procedure.
6.5

The "Deviation" Calibration Procedure

T50> cal dev
This procedure should not normally be invoked as part of any field maintenance. The
only conceivable time that it might ever be used, would be if a non standard maximum
deviation was required.
The first stage begins with the following message:
This procedure sets the Balance and Max Deviation Levels
Connect an audio signal generator to the Line 1 inputs
Set the output to be a sine wave, 388mV rms and 75Hz
Disconnect the RF connection to the PA
and connect a deviation meter to the exciter's BNC output.
Note that the nominal output power of the exciter's output is 1W. Whilst the power
level is not set to the maximum level, the deviation meter should either have an input
power rating of at least +30dBm, or suitable attenuation is required between the exciter
and the deviation meter. Note that for this test the nominal RF output frequency is
37.5MHz.
Enter + or - to increase or decrease the deviation,
and <RET> when the deviation is 5kHz
?
Here the user can hit the +, p, or P, keys to increase the deviation, or -, m, or M keys to
decrease it. In response, the firmware, which has opened up the maximum deviation
digital POT (U303) to maximum gain is adjusting the Line1 VCA accordingly.
When the deviation is as close to 5kHz as can be obtained, the User should hit their
Enter key.
RF Technology T50 Page 31