EDI DSTS-5A Manuale d'uso - Pagina 9

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6 CALIBRATING THE DSTS-5A

6.1 The load resistor can change if overheated by too much power. A large change in the

resistance will cause the voltage and reply readings on a depth sounder to change. The

load resistor should be checked any time abnormal readings are experienced.

6.1.1 Check the load resistance with the DSTS-5A power off. Place an ohmmeter

across the IN/OUT connector. The resistance for the factory installed load should

be 582 ohms +/- 10%. The resistance of a custom load at the IN/OUT connector

should read 22 ohms higher than the value of the installed load resistor. If the load

is out of spec, the unit should be taken apart and the load resistor replaced before

any further calibration or checks are done.

6.1.2 Run the supplied terminal program, DSTS_terminal.exe.

6.1.3 VOLTMETER CALIBRATION

Caution—Do not perform this procedure without a EDI DSTS calibrator

or other comparable pulse source.

6.1.3.1 The volt meter calibration is in the "extended menu". Type 't' to enter the

extended menu. Then type 'c' to start the voltmeter calibration routine. Connect

the EDI DSTS calibrator or other comparable pulse source to the IN/OUT

connector. After the indicated voltage readings have settled down, type in the

correct input pulse voltage in volts peak-to-peak and press 'enter'. A calibration

factor will be generated and stored in eeprom. Press the reset button and check

that the voltage reads correctly. If not, repeat the calibration.

Connect the DSTS-5A to a frequency counter and press the reset button. Set the

output to continuous by typing 'B' followed by 'enter'. Set output level to

maximum by typing l255. Set the frequency to 100 KHz by typing f10000 followed

by 'enter'. The frequency counter must read 100,000Hz +/- 10 Hz.

6.1.5 REPLY AMPLITUDE CHECK

6.1.5.1 Connect a scope (1 megohm input required) directly to the IN/OUT

connector with a short (< 3ft) cable. Set the frequency to 100 KHz (f10000) and

the level to maximum (l255). The voltage must read 140 mV p-p +/- 7 mV p-p.

This is a fixed factory setting and will not change unless the DSTS-5A has been

damaged by a severe overload.

6.1.6 OPTIONAL REPLY ATTENUATOR CHECK

6.1.6.1 Connect the DSTS-5A IN/OUT connector to a spectrum analyzer. Set

various levels to make sure the attenuator tracks properly. Note that the output

on the analyzer will be low because the 50 ohm input impedance of the

spectrum analyzer loads down the DSTS-5A output. If a high impedance

(>=100,000 ohm) probe is available, the readings will be correct and a level of

1 The EDI DSTS Calibrator produces a 400 volt p-p pulse burst with a frequency of 204.8 KHz, length of 325 uSec,

and a period of 80 mSec. Droop is less than 10 percent.

DSTS-5A Manual

Page 9

Rev 140930-300