Radcal Dynalyzer III User manual

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USER GUIDE
DYNALYZER
OPERATION MANUAL
Dynalyzer III Digital Display/Printer

Warranty for the Model M-96320 Dynalyzer Digital Display Unit
Radcal Corporation warrants that, in the event that any defects in material or workmanship should
develop within one year of the date of shipment, the company assumes full responsibility for
servicing equipment of its manufacture without charge upon return of the equipment to Radcal,
with shipping costs prepaid by the customer. Costs to return-ship by ground to customers will be
paid by Radcal if the repairs are warranty-applicable.
Radcal shall not be held liable for damages or delays caused by defects beyond making repairs or
furnishing replacement parts, not shall Radcal be liable for any defective material replaced without
Radcal’s consent during the period of this warranty. Radcal reserves the right to perform warranty
services at its own factory.
Non-Warranty Repairs
The calibration of this instrument was correct within specified limits when the instrument left our
factory. Radcal cannot be responsible for injury or damage resulting from improper use or
calibration errors which develop subsequent to our shipment of the instrument.
If Radcal determines that a fault has been caused by misuse, abnormal operating conditions, or
repairs by unauthorized personnel during the warranty period, repairs and shipping costs will be
billed at normal rates.
If the equipment is found to be in proper working condition, Radcal will return-ship the equipment
at customer expense.
Radcal Corporation
426 West Duarte Road
Monrovia, CA 91016-4591 USA
USA [phone]
Fax USA [phone]
email sales@radcal.,com
www.radcal.com
Radcal Part # MNL/S-3669
4078220 Rev:B2
Printed: JUN 2015
Copyright© 2009, 2011

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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Contents
Important ..............................................................................................................................................................2
Introduction..........................................................................................................................................................2
Description.........................................................................................................................................................2
Construction ......................................................................................................................................................3
Measured Quantities.....................................................................................................................................3
Predicted Maximum mAs Reading Inaccuracy for Selected Exposure Times .............................................6
Calculated Quantities....................................................................................................................................6
Operation..............................................................................................................................................................8
Operation..............................................................................................................................................................9
Specifications ....................................................................................................................................................9
Printer............................................................................................................................................................9
RS-23-2 Connector.......................................................................................................................................9
Initial Setup and Self Test .................................................................................................................................9
Triggering Sources..........................................................................................................................................10
External Trigger...........................................................................................................................................11
Auto Trigger ................................................................................................................................................11
Manual Trigger............................................................................................................................................11
KV and MA Trigger Mode Operation ..........................................................................................................11
Trigger Level ...................................................................................................................................................12
kV Measurement Delay...................................................................................................................................15
Fluoroscopic Current Measurements (0-20 mA).............................................................................................16
Window Delay Mode Operation.......................................................................................................................16
Exposure Number Window and Recall Button................................................................................................18
Clear Reading .................................................................................................................................................18
Reset...............................................................................................................................................................18
Coefficient of Variation Measurement.............................................................................................................18
Applications .......................................................................................................................................................20
Typical Operating Sequence...........................................................................................................................20
Recommended Procedure for Verification of X-ray Equipment Calibration....................................................21
X-Ray Tube KVP (A + C), Transformer Balance A & C, and Exposure Timer Verification........................21
X-ray Tube Milliampere Station Verification................................................................................................21
Grid Pulse System Measurement ...................................................................................................................21
Printer .................................................................................................................................................................23
Loading Paper into the Printer.........................................................................................................................23
Changing the Printer Ribbon...........................................................................................................................23
Output Port.........................................................................................................................................................24
RS232 Port Settings........................................................................................................................................24

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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Important
READ THIS MANUAL
Serious measurement errors may result from improper use of this equipment or improper
interpretation of readings.
Introduction
As an element of the Dynalyzer system, the Digital Display embodies a wide range of x-ray
measurement features for rapid calibration, compliance testing, and troubleshooting. When used
with the Dynalyzer II or III High Voltage Unit, conventional oscilloscope and voltmeter, complete
analysis of the system under test is possible. It provides:
•Expanded versatility, more exposure data and compliance testing capability and faster,
easier data interpretation
•Automatic exposure calculations, decreasing manual computational errors
•Greater data accuracy (traceable to the US National Bureau of Standards)
•Stored data in the temporary digital display memory for statistical measurements and data
recall
•Data recorded in hard copy form for permanent record purposes with the integral printer.
The measurement features include:
•kVp (anode, cathode, and anode + cathode)
•mA and mAs
•Exposure time
•Standby and boosted filament current
•Coefficient of variation calculations for kV, mA, and time for up to 10 exposures
•Fixed window (sampling period) with an adjustable delay, for analyzing waveforms in
equipment such as falling load types of generators and automatic filament/mA control
systems
•Storage and recall capability of exposure data for as many as 10 consecutive exposures
Description
A microprocessor-based circuit controls all functions – from exposure measurements to data recall.
Troubleshooting is simplified by the inclusion of self-diagnostic tests for locating circuit
malfunctions.
Two digitally processed and displayed trigger modes are available:
•Percent – Selects a percentage of a reference level (previous exposure) for kVp and mA
•Preset – Selects an absolute value of kVp, mA, or an external source
The preset mode obviates the need for making a reference exposure and resetting the trigger
between exposures, regardless of the time elapsed.
Technique factors are stored in the memory of the digital display unit for up to the last 10
consecutive exposures, any of which can be sequentially recalled. Coefficient of variation
calculations are made automatically and can be instantly displayed on the front panel.

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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Construction
A louvered aluminum cover with a luggage type handle encloses a rugged, yet lightweight
aluminum chassis. Four 4-digit LED displays show all x-ray parameters in a clear logical
arrangement and are protected, along with the front panel controls, by an extension of the cover.
The rear panel contains a selectable line voltage cable receptacle, bulkhead receptacles for
connection to the Dynalyzer II or III High Voltage Unit and BNC connectors for an auxiliary
oscilloscope. Modular construction is used throughout.
The following specifications refer to the measurement accuracy of signals provided at the Digital
Display input and may add to or subtract from inaccuracies in the Dynalyzer H.V.U.
Errors, in absolute terms, would typically be less than 50% of the worst case values stated. Errors
(from one measurement to another) would typically be less than 25% of the worst case values
stated.
Interface Requirements:
Compatible with both Dynalyzer II and III High Voltage Unit.
Measured Quantities
(See note 1)
kVp (peak kilovoltage)
Anode to Cathode 20 to 150 kVp ± (0.75 kV + 0.5% of reading)
Anode Only 20 to 82.5 kVp ± (0.6 kV + 0.5% of reading)
Cathode Only 20 to 82.5 kVp ± (0.6 kV + 0.5% of reading)
Internal Resolution .03125 kV (
1
/32 kV)
msec (exposure time) 0.7 to 9999 msec ± (0.25 msec + 0.5% of
reading) See notes 2 and 3.
Internal Resolution 1 microsecond
Filament Amps 0-20 Amps rms ± (0.05A + 0.7% of reading)
See note 5.
Internal Resolution 1.25 mA
Frequency Response Within 1% of 60 Hz value where frequency <
100 KHz and filament current value > 2 amps
mAs – Normal Mode (millamperes x
seconds)
Range 0.1 to 2621 mAs ± (0.1 mAs + 0.6% of reading
+ 1 mAs per second of exposure) See notes 2
and 5.
Internal Resolution 0.04 mAs
Frequency Response > 1KHz
mAs – Fluoro Mode (milliamperes x
seconds)
Range 0.01 to 131 mAs ± (0.1 mAs + 0.6% of reading
+ 0.1 mAs per second of exposure) See notes
2, 3, and 5.
Internal Resolution 0.002 mAs

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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Figure 1: Typical Dynalyzer III System

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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75VA MAX 2A
120V 1A 240V
120/240 VAC 50/60 HZ
901 10,000 VDC OUT-VCO U22 ANLG BD.
902 BCKGRND RADIATION ABOVE 1mR/Sec
904 % TRIGGER SELECTED IN EXT. MODE
905 10,000 VDC OUT U5,U12, OR U7 ANLG BD.
906 10,000 VDC OUT U13 OR U6 ANLG BD.
907 EXPOSURE TIME EXCEEDS 999mSec.
909 LESS THAN 10EXP'S USED FOR STAT. AN.
ERROR CODES
000 SYSTEM O.K.
903 BACKGROUND RADIATION ZERO
908 mAS LIMIT EXCEEDED
DATAOUT
MA
A + C
KV
H-V UNIT
EXT TRIG
EXT TRIG
WARNING
DISCONNECT FROM MAIN POWER
BEFORE SERVICING
Input Power Connector - Allow rapid
fuse charging and line voltage
changeover (120/240 VAC)
+5V regulation
pass transistor
High Voltage Unit Interconnect
Socket - Accepts cable from
Dynalyzer II or Dynalyzer III High
Voltage Unit
External Trigger BNC Connector - See
SPECIFICATIONS
A + C Kv Connector Scope input;
internally summed to eliminate
need for differantial scope input
MA BNC Connector - Scope input;
allows viewing of anode current
Figure 2: Outline Data
Figure 3: Rear Panel Description
R
9.88 REF
[251]
15.63 REF
[397]
16.57 REF
[421]
7.56 REF
[192] 6.88 REF
[175]
11.63 REF
[295]
dimension in inches [mm]

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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Predicted Maximum mAs Reading Inaccuracy for Selected Exposure Times
RAD Mode (1 mV/mA as selected at High Voltage Unit)
Exposure Time
Displayed
(msec)
mAs Displayed
10 100 500 1,000 2,621*
10 ± 0.17 ± 0.71 ± 3.1 ± 6.1 ± 15.8
100 ± 0.26 ± 0.80 ± 3.2 ± 6.2 ± 15.9
1,000 ± 1.16 ± 1.7 ± 4.1 ± 7.1 ± 16.8
9,999 ± 10.16** ± 10.7 ± 13.1 ± 16.1 ± 25.8
FLUORO Mode (20 mV/mA as selected at High Voltage Unit)
Exposure Time
Displayed
(msec)
mAs Displayed
0.4 2 10 50 131*
10 ± 0.10 ± 0.11 ± 0.16 ± 0.40 ± 0.89
100 ± 0.11 ± 0.12 ± 0.17 ± 0.41 ± 0.90
1,000 ± 0.20** ± 0.21 ± 0.26 ± 0.50 ± 0.99
9,998 ± 1.10** ± 1.11** ± 1.16 ± 1.40 ± 1.89
*Maximum measurable value of mAs.
** Not recommended; usefulness limited by inaccuracy.
Calculated Quantities
The following values are calculated from some combination of the measured quantities. The
accuracy of a particular reading must therefore be determined by calculating the possible error in
the two measured quantities and combining these errors. Note that a large final error can occur
when either of the measured quantities is very small.
mA (average anode current)
Radiographic mode 0.1 to 9999 mA (See note 5.)
Fluoro mode 0.01 to 500 mA (See notes 3
and 5.)
Triggering Percent (2 to 100%) Preset
kVp Trigger Level
Range (actual) 2.4 to 200 kV 4 to 200
Increment 0.4 kV 0.4 kV
Accuracy ± (2% + 0.4 kV) ± (1% + 0.4 kV)
mA Trigger Level (Normal Mode)
Range (actual) 40 to 9999 mA 40 to 999 mA
Increment 40 mA 40 mA
Accuracy ± (2% + 40 mA) ± (1% + 40 mA)
mA Trigger Level (Fluoro Mode)
Range (actual) ± 2 to 500 mA 2 to 500 mA
Increment 2 mA 2 mA
Accuracy ± (2% + 2 mA) ± (1% + 2 mA)
External Trigger Level
Range (actual) Not allowed (error code 904) 3.0 to 10.0 volts
Increment 0.1 volts
Accuracy ± (0.3 + 5%)
Rise of fall time lag, max 150 usec
Input impedance 1K Ohm
Auto Trigger Update Rate Approximately once per second, 0.75 second sample time

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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Auxiliary Functions (coefficient
of Variation Sample number) 10 consecutive exposures
Delay Ranges
kV delay 0-20 milliseconds
Window delay 20-999 milliseconds
Window width (sampling time) 20 milliseconds
Input Power Requirements
Built-in printer 104-125 VAC, 50/60 Hz @ 76 watts
208-240 VAC, 50/60 Hz @ 76 watts
Without printer 104-125 VAC, 50/60 Hz @ 40 watts
208-240 VAC, 50/60 Hz @ 40 watts
Fuse 2 Amp SB for 120 V power
1 AMP SB for 240 V power
Operating Temperature Range 0-50°C (32-122°F)
Storage Temperature Range 0-70°C (32-158°F)
Operating Relative Humidity 90% @ 40°C (104°F)
Storage Relative Humidity 95% @ 60°C (140°F)
Dimensions See Outline Data
Weight (approximate)
With printer 22 lbs (10 kg)
Without printer 18.5 lbs (8.4 kg)
Notes:
1. Due to cable capacitance, mA and A+C kV readings taken from the rear panel BNC
connectors may be degraded from the readings taken from the equivalent connectors
on the High Voltage Unit by the following amounts:
omA by ± (5 mV. + 1%)
okV by ± (10 mV. + 1%)
2. mAs and exposure time are measured du ring the period that the trigger signal is
above the trigger threshold. Therefore, the waveshape of the trigger signal and the
value of the trigger threshold can profoundly affect these measurements.
3. The low mA (Fluoro range) is selectable at the Dynalyzer III HVU. With this range
selected, the normal scale factor (1 mA = 1 mV) is multiplied by 20 (1 mA = 20 mV).
4. Requires minimum 65 msec exposure for rated accuracy.
5. Use of the “Fluoro” mode is strongly recommended when working with mA values
under 20 mA.

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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PERCENT/PRESET
MODE
TRIGGER
FIL. AMPS
DYNALYZER III - DIGITAL DISPLAY
1000 MSECOFF
MSEC. MAS MA
CATHODE
A + C
ANODE
WINDOW DELAY
020MS
KV DELAY
TRIGGER LEVEL
I
N
C
R
E
A
S
E
ERROR
TEST
NORMAL
TRIGGER SOURCE
EXT
AUTO KVP
MA PROCEDURE
COEFF
VAR
PRESET
PERCENT
POWER
R
RESET
OFF ON
RECALL
EXPOSURE
EXT MA KVP
PRINTER
OFF AUTO PRINT
NUMBER
EXPOSURE
TRIGGER
MANUAL READING
CLEAR
TRIGGER LEVEL - Multi-turn poteneiometer
allows user to dial in PRE-SET or PERCENT
trigger levels prior to exposure. The trigger level selected is read at
Preset/Percent display. Trigger level is
only applicable when kVp, mA or EXT
trigger source is selected.
WINDOW DISPLAY - Single turn potentiometer.
Upon acknowledgement of system trigger,
delays reading of all data excluding time
by a preset time interval. Window delay time
can be from 25 to 1,000 mS. This mode is
indicated by adjacent LED indicator. To
enable this mode, control can be set to desired delay period and either MANUAL
TRIGGER, CLEAR READING or RESET
push-buttons momentarily depressed.
TRIGGER SOURCE - Five- Position
switch for trigger source selection.
EXT - This switch position allows
system to trigger from an external
source.
AUTO - This position allows system
to trigger from the internal clock.
(Internal update rate approximately
1.0 sec.)
mA - This position allows system
to trigger from mA source.
kVp - This position allows system
to trigger from kVp source.
TRIGGER MODE - Two-position
switch, user selectable for Trigger
Mode of operation. PERCENT - This trigger mode of
operation is used in conjunction
with the "Trigger Level" potentiometer.
The user presets the trigger level
prior to exposure by dialing in
a trigger level of typically 10% of
pulse height for single-phase and
75% for three-phase.
PRESET - This trigger mode of
operation is also used in conjunc-
tion with "Trigger Level" potentio-
meter. The user presets the trigger level prior to exposure by dialing in an absolute kVp or mA value.
PROCEDURE - Three-position switch
for Coefficient of Variation measurement.
System Test and Normal.
COEFF. VAR. - Calculates co-
efficient of variation for up to the
last 10 exposures and outputs the
result to the corresponding display.
The FIL, AMPS, LINE N/L and LINE
functions are not applicable in this
mode.
TEST - In this mode, the system
performs a test of its own analog
and digital circuitry and allows
background radiation nulling for
the radiation probe. Upon error
detection, system signals an error
code and lights the "ERROR" LED
indicator.
kV DELAY - Single turn potentiometer.
Upon acknowledgement of system trigger,
this potentiometer delays system reading
of kV for a preset time interval, allowing
only the trailing portion of the pulse to affect
the reading. kV reading can be delayed
up to 20 mS.
used. position ind EXT Trigger Inputs not that the trigger source be in EXT operation is used, it is recommended *When MAN TRIGGER mode of
CLR READING - This push-button,
when depressed, clears out the
current exposure data corresponding
to the EXPOSURE NUMBER
EXPOSURE RECALL - This push-button,
when depressed, is used to recall each
of the 9 (or fewer) previous exposures.
Depressing this switch decrements the Exposure Number and displays past
exposure data.
RESET - This push-button, when
depressed, clears all registers and
re-initializes system for the start
of the next exposure sequence.
PRINTER - This multi-function
switch is used to control printer operations. A LED indicator, when
lit, signifies printer ON.
PRINT - This is a momentary (hand
held) switch position. When in upper position the most current exposure
data is printed.
OFF - Disables printer from printing.
LED indicator OFF.
AUTO - When depressed, the switch
is locked in an "ON" position. The
system automatically prints
exposure data after each exposure.
POWER - When in the "ON" position
the power ON/OFF LED indicator
should be lit.
*MANUAL TRIGGER - This push-button,
when dwpressed, activates readouts
of standby FIL/AMPS and Line Volts, kVp,
mA or mAs, and mR. If printer is in AUTO position the data read is routed to the printer.
MSEC - Measures exposure time.
MA/MAS DISPLAY - Measures
average current or current integrated
over time. Values for both positions
are stored and can be selectively
displayed after the exposure.
kVp DISPLAY - Measures kilovolts
peak for Anode, Cathode or Anode
+ Cathode. Reading deisred must
be selected prior to exposure.
FIL, AMPS. Measures AC rms
current during exposure.
To measure standby filament
current prior to exposure, depress
MANUAL TRIGGER.
Figure 4:

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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Operation
Specifications
Printer
Characters 116 characters, 5 x 7 font, 24 characters per line
Data Per Line 24 characters per line
Duty Cycle Continuous
Print Rate 1.7 lines per second
Input Buffer 6900 characters
Paper Advance Paper feed switch
Paper Supply Plain paper, 2-1/4”W x 1,6” OD
RS-23-2 Connector
Connector DB-9 (9-pin)
Baud Rate 2400
Data Bits 8
Stop Bits 1
Parity None
Initial Setup and Self Test
1. Determine input line voltage (104-125 or 220-240 VAC) and ensure that input power connector
is properly set. See Figure 5.
2. Plug the Digital Display power cord into the same source of power used for the High Voltage
Unit. This should be the same for AC branch circuit and preferably the same receptacle. Be
sure the power source is equipped with an approved earth ground.
3. Place the POWER switch in ON position or depress RESET if already ON. All displays should
read zero.
4. Verify correct operation by placing the Digital Display in the TEST mode. To use the TEST
mode:
a. Turn Voltage Display Select switch to A or C.
b. Turn mA/mAs Display switch to mA.
c. Turn TRIGGER SOURCE switch to kVp; kV Delay and Window Delay fully
counterclockwise (OFF).
5. Turn PROCEDURE switch to TEST position. After about 10 seconds the self testing cycle is
complete. No information should be visible in the Percent/Preset window. The A + C window
should indicate 10.00 ± 0.3. The mA window should read “5226”. If a three digit Error Code
(other than 903) appears in the Percent/Preset window, this is an indication of a malfunction or
improper control setting.

Dynalyzer – Digital Display/Printer OPERATION MANUAL
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NOTE: Background nulling will provide an incremental improvement in mR accuracy and is
only useful when exposure rates below 50mR/sec are encountered.
6. Connect the twenty-foot cable (supplied) between the High Voltage Unit and the Digital
Display. This cable is connected to the H.V. Unit connector on the Digital Display, and the
Digital Display connector on the High Voltage Unit. Both ends are identical. The connector
locks with a half turn.
7. Connect an oscilloscope, if desired, to oscilloscope outputs on the Digital Display. Plug the
scope power cord into the same grounded receptacle as the Display and High Voltage Unit.
The A + C output is 1 volt per 20 kV; the mA output will be 20 mV per mA if FLUORO is
selected, or 1 mV per mA if RAD is selected at the High Voltage Unit.
8. Reset the PROCEDURE switch on the Digital Display to NORMAL. The unit should again
display 0’s.
CAUTION: As 5 foot long high voltage cables are normally used to connect the Dynalyzer
III High Voltage Unit to the x-ray tube (necessitating that the HVU be placed
on the table) the possibility exists that the HVU may be inadvertently placed in
the primary beam. If this occurs, the SF6 gas used to insulate the internal
components in the tank section of the HVU may become sufficiently ionized to
cause gross measurement errors, e.g., 20 to 30 kV. In order to guard against
this possibility, the user must be careful to angle the tube away from the HVU
or close the collimator shutters.
Figure 5: Voltage Selection
Triggering Sources
There are several different methods of starting or triggering the Dynalyzer III Display measurement
and analysis functions for an x-ray exposure. The TRIGGER SOURCE switch is used to determine
which trigger source is to be used.

Dynalyzer – Digital Display/Printer OPERATION MANUAL
11
External Trigger
The external trigger mode is provided for special applications. Any trigger signal must conform to
the voltage range (3-10 VDC) and duty cycle listed in SPECIFICATION.
Auto Trigger
AUTO trigger is the most useful when setting up filament circuits in the generator. The Display
operates as a DVM (digital voltmeter) for all inputs except exposure time and the display is
continuously updated. Auto triggering can also be used during fluoroscopic exposures particularly
when measuring automatic brightness control equipment effects on mA and kV.
When performing filament current measurements the current must maintain itself for 65 msec
because the rms converter in the Digital Display requires 65 msec to settle to its rated accuracy.
Most x-ray generators have the filament at rated current before the exposure begins, and this
enables the Digital Display to accurately measure the current during an exposure of less than 65
milliseconds.
In the AUTO mode the Digital Display provides one second updates of the filament current to
enable adjustment of the filament current controls.
The Dynalyzer III High Voltage Unit filament current sensor is frequency compensated from 20-
20,000 Hz. This enables the system to work with conventional x-ray generators, and with certain
CT generators employing high frequency power supplies. The response of the sensor falls off
rapidly beyond 20 kHz.
Manual Trigger
This switch will function with the trigger selector in any position. It is recommended that the
selector be in EXT if no external trigger source is being used. This pushbutton, when depressed,
causes the display to read the standby filament current. It can also be used during a fluoro
exposure to read kV and mA. If a printer is included in the system and is in the AUTO mode, the
data is printed.
KV and MA Trigger Mode Operation
The kVp and the mA trigger modes allow the user to either set a percentage of the prior exposure
at which the unit triggers by selecting PERCENT with the Trigger Mode select switch, or to select
an absolute trigger level by selecting the PRESET trigger mode.
In order to use the Percent mode, data must be stored in the Display memory. This data becomes
a ‘reference’ exposure, provided it exceeds 20 kVp (for kV triggering) or 40 mA (for mA triggering).
The following exposures in the series are triggered in this mode at a percentage level displayed in
the Percent/Preset window of the last previous exposure level. It is important to determine that any
noise produced by contactors or motor starters, etc. does not cause a false trigger. This can be
corrected by raising the trigger level (increasing the signal-to-noise ratio) to avoid the influence of
false triggers, or by turning the TRIGGER MODE switch to PRESET.
If the trigger level is too low the system may “latch-up” on noise. The system may appear to be
inoperative. Turn trigger level knob clockwise, and press RESET. The trigger level will jump to the
new value.
The minimum trigger level in PERCENT is set to the equivalent of 20 kV and 40 mA to minimize
noise problems. This value is independent of the percent selected.

Dynalyzer – Digital Display/Printer OPERATION MANUAL
12
Using the Preset mode allows triggering on the absolute level of kV or mA, which is displayed
directly in the Percent/Preset window. In this mode the Display eliminates any fluctuation in the
trigger level during a series of exposures. The effects of pre-trigger pulses, x-ray tube instability,
and other transient phenomena will not change the trigger level. The design minimums of 4 kV and
20 mA should be observed, however.
In the PERCENT mode, if a series of exposures is made with increasing kVp, the trigger value is
always in range. However, if the series is made with decreasing kVp, it is possible that the change
will be great enough, especially if the level is set at 75% or above, for a trigger not to occur. In this
case, depressing the CLEAR READING button resets the trigger register to a nominal value (20
kVp). Depressing the RESET pushbutton accomplishes the same purpose, but this resets the
display memory, and wipes out the background nulling calibration of the radiation probe that was
achieved during the Self Test procedure. If the button is inadvertently depressed, the radiation
probe should be re-zeroed. Refer back to “Initial Set-up and Self Test”.
Trigger Level
Proper setting of the trigger level is required in order to obtain accurate time and tube current data.
Exposure time and current are intimately related as current (mA) is a value calculated from mAs by
the Digital Display.
mA = mAS
Exp. Time
For exposures of arbitrary lengths, no other averaging scheme can yield as accurate a result as
this formula.
For single-phase exposures, use as low a trigger level as possible (consistent with the elimination
of any electrical noise present) to obtain accurate readings. The level should be set to 10%. Lower
trigger level settings may cause false triggering but may be used if conditions permit (the minimum
kV trigger value obtainable will be 5kVp.) Increasing the trigger level results in shorter than true
exposure times. In addition, on short exposures, low mA values may not be integrated, resulting in
an mA error of +40%, if the trigger level is set to maximum. Erroneous exposure times will also be
observed.
Figure 6: Effect of 10% Trigger Level on Exposure Time
10% TRIGGER LEVEL
0% TRIGGER LEVEL
ERROR AREA
MEASURED
READ TIME
time error = f 360°
2 sine-1
10% level = 0.53 ms error

Dynalyzer – Digital Display/Printer OPERATION MANUAL
13
Figure 7: Effect of 50% Trigger Level on Exposure Time
Single-phase generators should produce time values that are multiples of 1/120 of a second (8.33
milliseconds). Some generators start up with a small pulse phased 20° (approximately) ahead of
zero crossing. This voltage will, in many cases, be enough to begin the timing cycle. The deviation
in total exposure time from a fixed number of cycles may represent this time, unless of course the
exposure termination is not obtained at zero crossing. This effect will be most noticeable in short
exposures such as 1/120 and 1/60 second.
Figure 8: Single-Phase Generator Exposure Time Measurement
The proposed convention for timing measurements of three-phase equipment is to measure the
voltage pulse width from intersection with 75% of the peak voltage. Some manufacturers use other
values in the calibration of their equipment. The LEVEL control must be set to that value.
TRIGGER
READ
TIME
1/60 SEC.
50% level= 2.7 ms. error
ERROR AREA
50% TRIGGER LEVEL
MEASURED
READ TIME

Dynalyzer – Digital Display/Printer OPERATION MANUAL
14
Figure 9: Use of 75% Trigger Level for Three-Phase Exposure Time Measurement
The mA trigger capability is especially useful in grid pulsed systems, as pulsed-grid tubes such as
sine units are, in general, operated with a constant potential capacitor bank or a continuously
present three phase voltage. Triggering on voltage is therefore not possible. Because of the fast
current rise time, the trigger level is not critical, and may be set according to the manufacturer’s
instructions or at 75% to be consistent with the voltage trigger point. The exposure should consist
of only one pulse or the Dynalyzer will reset.
Capacitor discharge generators operate by turning off the negative bias present on the grid of the
x-ray tube. The exposure time is a function of this negative bias pulse width. The anode current
discharges the capacitors until the voltage drops below some predetermined threshold. A kV
trigger cannot be used in this case because the voltage is present before the exposure begins. mA
trigger will give the true exposure time if the trigger level is properly set. The mA waveform will
almost be a square wave with fast rise and fall times.
An external trigger may be used if an exposure signal is supplied by the generator.
mA trigger is also useful in systems where long cable lengths and moderate mA’s (25-100) cause
the cable to hold a charge at the end of the exposure. The kV waveform will appear to have a long
tail, and the measured exposure time will be unnecessarily long if kV triggering is employed. See
the following figure:
75% TRIGGER
LEVEL

Dynalyzer – Digital Display/Printer OPERATION MANUAL
15
Figure 10: Use of mA Trigger to Compensate for Cable Capacitance
By triggering on tube current, the exposure time will be read when the emission stops. Units with
biased focal spots will also tend to exhibit this phenomenon. Because of emission cut-off (typically
below 20 kV) in grid bias situations, the mA trigger may be very useful to prevent the cable
discharge period recorded on kV triggering from affecting the measurements.
kV Measurement Delay
The kV measurement delay is used to delay the measurement of peak kV for a period after
triggering while the other factors are being measured. This delay can be adjusted up to 20 msec
and is controlled by the kV Delay potentiometer which otherwise should be set to zero.
Many three-phase generators may exhibit an overshoot in voltage during the first pulse due to
phasing and/or magnetic saturation effects. Although the additional radiation produced by this
pulse may be ignored in long exposures with a lower average voltage, the ratings for the tube and
cable may be exceeded by this overshoot, and its presence should be identified. In short exposure
times this overshoot can cause unexpected firm darkening. The overshoot can be observed on a
scope. Provision has been made to obviate the need for the scope by providing the adjustable
delay. An exposure should be made with the kV Delay control set to zero to capture the maximum
kVp level. The delay control can then be adjusted to 20 ms. This should be sufficient to change the
kVp measuring region so that the overshoot is ignored. The delay will not affect current or time
measurements. See the following figure:
TRIGGER CABLE CHARGE
END OF
EXPOSURE
mA
mA
kV

Dynalyzer – Digital Display/Printer OPERATION MANUAL
16
Figure 11: Use of kV Delay to Compensate for kV Overshoot
Fluoroscopic Current Measurements (0-20 mA)
Dual ranging mA has been provided on the Dynalyzer III High Voltage Unit to improve low mA
accuracy. Unless the High Voltage Unit is zeroed while connected to the Display, errors can be
introduced. The “mA zero” control is a screwdriver potentiometer adjustment requiring slight motion
to trip the expected drift of several millivolts. This zero is temperature sensitive. As the system
reaches thermal equilibrium, the zero on the High Voltage Unit must be readjusted if it drifts.
The mA zero setting, if slightly above true zero, may be verified by triggering the Digital Display on
AUTO with the fluoroscopic current set to zero (generator off). Any mA reading on the display
would represent the combined offset error of the High Voltage Unit and the Display Converter
Circuit (which should not be field adjusted). This value should be subtracted from the reading
during operation.
The dual range scale conversion factors of 1 millivolt per milliampere for radiographic and 20
mV/mA for fluoroscopic measurements are controlled by a switch on the High Voltage Unit. If AC
noise is introduced on the signal line, the temperature-sensitive drift of the circuitry will not be
averaged out, therefore care in grounding must be taken (the HVU and Display should be plugged
into the same receptacle with a good earth ground.) A differential input has been provided on the
mA line circuitry so that common mode and ground noise is reduced. A separate return is provided
for the mA signal into the Dynalyzer III High Voltage Unit.
Window Delay Mode Operation
A new feature has been added to the Dynalyzer III which enables viewing any 20 msec part of the
first second of an exposure.
To use this function, the WINDOW DELAY control must be turned ON past its minimum delay time
of 50 msec, at which point the associated LED lights to indicate that the Window Mode is selected.
The length of window delay is displayed in the MSEC exposure time window. The MANUAL
TRIGGER, CLEAR READING, or RESET pushbuttons must be momentarily depressed.
In a falling load type generator, with several current values and time intervals between these
values, the window delay function is needed to set the kVp and emission at each step.
kV OVERSHOOT
kV MEASURED
kV DELAY SET
FOR 20 ms

Dynalyzer – Digital Display/Printer OPERATION MANUAL
17
Falling load mA waveforms are illustrated below. Turn the WINDOW DELAY control to display
more than 50 msec in the MSEC display.
Figure 12: Use of Window Delay with Continuous Falling Load Generators
Figure 13: Use of Window Delay with Stepped Falling Load Generators
In the example above, set T, the window delay, to 200 mS. This enables measurement of the
second step of the above waveform. If a scope is not available, make a series of exposures and
record kV/mA as a function of delay time.
The user should be cautioned that the mAs displayed is not the mAs of the entire exposure, but
only the mAs of that small section. The mA is averaged over a 20 msec interval and is derived
using the formula:
mA = mAs
0.02
Other suggested applications are studies of automatic filament/mA control systems where it may
be desired to measure the mA during the first pulse and at some time thereafter, in which case turn
the WINDOW DELAY control OFF, make an exposure and record the data. The window position
WINDOW
DELAY
TO 1 SEC.
200 ms
20 ms
WINDOW
WIDTH