DGC IV calibration

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Years ago RBD Instruments had our DGC IV manufactured by JC Controls.  The DGC IV is basically the same thing as a IG4500.
Although we no longer produce the DGC IV, there are still a few of them in the field.  The calibration procedure is listed below.


PR7(VREF)Reference Voltage Adjust                                                          Direction are with the front

PR4(TC1 Z)TC1 Zero Adjust                                                             of the IG4500 facing you.

PR6(TC2 Z)TC2 Zero Adjust                                                                            N

PR3            TC1 Gain Adjust                                                                                    W –+– E

PR5            TC2 Gain Adjust                                                                                         S

R1(EMIS)    Emission Adjust

PR2(ELEC)Electrometer Adjust


Power Supply Tests ( Ground)

  1. Attach Tester box to controller and check voltages on computer or do steps B,C,D,E
  2. Test -15,+15,+5 from 8 Pin Power Connector Pins   2,3,4.
  3. Turn on Ion Gauge
  4. Test +180 V From Grid Pin (Outside) of tube to Ground.
  5. Test +150 V from Grid Pin to Fil Pin (Outside to Inside) of tube.
  6. Check Degas

(1) Reference Voltage Adjustment

  1. Connect DC DVM from R14{E} to ground R31{E}
  2. Turn on IG4500 while holding down the SELECT switch,.
  3. While holding down the SELECT Switch, adjust PR7 (VREF) until the DC voltage is 10.000 ( +/- .001 )
  4. Release Select Switch and Check off Recorder output box
  5. Turn Power off and on, check that all the LED light up, if so check off Digit(LED) Test

(2) TC1 & TC2 Zero Adjustment

  1. Connect TC Cable to TC1 Input on back of IG4500.
  2. Connect a TC tube that is at Atmosphere to the cable.
  3. Connect DC DVM from R26{E} to ground (R31{E})
  4. Adjust PR4(TC1 Z) until DC Voltage is .133 VDC. (+/- .005 )
  5. Do the same with TC2, Using TC2 Input, R33{E} & PR6(TC2 Z).

(3) TC1 & TC2 Gain Adjustment

  1. Connect TC Cable to TC1 Input on Back of IG4500.
  2. Adjust PR3 through the back panel until the main display is the same vacuum as the Test Tube. Because TC Tubes work by Heat, give the tubes time to readjust after the pot is turned.
  3. Do then same with TC2, Using TC2 Input, Bar Graph & PR5.


(4) Emission Adjustment

  1. Use tester box or connect a current meter in series with Pin 3 of J1 ( Power Connector ).
  2. Connect IG cable to unit and a IG Test Tube. Connect the current source to the BNC on the unit.
  3. Turn on power and turn on ion gauge tube. Use current source to get to 10 mA range
  4. Adjust PR1 (EMIS) until you get 10.0 mA (+/- .05) on current meter.
  5. Use current source to switch down to 1 mA range, emission should be 1.00mA on current meter, Record current.

(5) Electrometer Adjustment

A. Connect current source to IG4500, set to 1uA. Turn on Ion Gauge.

B. Adjust PR2 (ELEC) so IG4500 displays 1.0-04.

C. Repeat Step B for 1nA=1.0-08, 100pA=1.0-09.

D. Also record for 10pA, it should be 1.0-10. (+/- 2.0)


(6) Setpoint & EEPROM

A. Check that the relay turn on and off by listening for them to click

B. Use the computer to set the serial number.

C. Turn unit off and on, Check serial number in “Edit Window” by entering =R#


Technical Modes of IG4500

* Enable Adjust Mode

This mode is for turning the System Enables on and off. It is entered by pressing and holding down the [ION] & [SELECT] buttons while turning on the main power . The display will show The Enable Name followed by either On or Off.

IGS Enables

Enable Name Description
F Filament Enable ( Display Mode )
Fd Full Duplex RS-232 Communication
C1 Code 1 enabled – Filament Overdrive
C2 Code 2 enabled – Under Vacuum, No Collector
C3 Code 3 enabled – Over Vacuum
A Averaging Enabled
E Emission Ranging Enabled


To Adjust the enables press the [ION] switch to select the different enables and the [DEGAS] switch to change from on to off. The Default for the IG4500 is All enables on.

** Timer and Control Mode

This Mode displays the timer value from the electrometer circuit. The value is a 6 digit Hexadecimal number. To put it on the 5 digit display either the lower 5 or the upper 5 digits will be displayed depending on if the high digit is a 0 or not. The Units LED’s are used as status LED’s


Display Unit LED’s

LED Name Status
Torr 25’th Bit of timer
Min Averaging On
mA Full Emission On


Mode 8 is entered by turning the Display switch to Emis. , then press the [ION] & [DEGAS] at the same time. The [ION] button will turn the Averaging on & off, you should make sure Averaging is disabled before adjusting it manually or else the controller will probably switch it back. The [DEGAS] button will switch between Full and 1/10 Emission Current.


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