| 2 Input Channels |
| 125MHz capability on each channel. |
| 8-digit readout |
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Use P6106A Probe
The DC 503A offers a broad range of measurement features. The instrument has two input channels, A and B, each with 125 MHz capability. Each channel has separate triggering level, triggering slope, attenuator, and coupling mode controls. Eight measurement functions are available with the DC503A, and an averaging feature allows averaging of 1 to 10 occurrence of the signal of interest. Signals to be counted or timed can be applied to channels A and B via the front panel BNC connector or through the rear interface connection. The DC503A features an easy to access front panel and an LSI-based design for increased instrument reliability.
Option 1 = Replaces the internal 10 MHz time base (clock) circuit with a self-contained proportional temperature controlled oven oscillator for increased accuracy and stability.
The DC 503A Universal Counter/Timer is designed to operate in a TM 500-series power module.
The instrument has two input channels, CH A and CH B, each with 125 MHz capability. Each channel has separate triggering level, triggering slope, attenuator, and coupling mode controls.
The DC 503A has eight measurement functions: FREQUENCY A, PERIOD B, WIDTH B, TIME A-B, RATIO A/B, EVENTS A DURING B, TOTALIZE A, and TIME MANUAL. All of the modes except FREQUENCY A, TOTALIZE A, and TIME MANUAL have the capability of averaging the selected measurement over a range of 1 to 10(exp 8) times the input signal. The signals to be counted or measured can be applied via front panel bnc connectors or throught the rear interface.
The triggering level for each channel can be monitored via the front panel or the rear interface
connections. The buffered voltage available at these connectors corresponds to the trigger levels set by the front panel controls.
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The output of the internal signal shaping ciruits can also be monitored via front panel connectors.
These shaped signal outputs are useful in setting the triggering points on complex waveforms.
Measurement results are displayed in an eight digit LED readout. The decimal point is automatically positioned and leading zeros are blanked. Single annunciators (LEDs) are used to indicate register overflow, active gating interval, and the frequency or time units associated with the measurement being made.
The DC 503A can be equipped with an optional, oven controlled, 10 MHz crystal oscillator to obtain a highly stable and precise internal time base. Both the optional oscillator and the standard 10 MHz time bases provide 100 ns single shot resolution.
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ELECTRICAL CHARACTERISTICS
| Characteristics | Performance Requirements | Supplemental Information |
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| CH A and CH B INPUTS/OUTPUTS |
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| Input Frequency Range |
| Front Panel |
| DC Coupled | 0 Hz to >= 125 MHz. |
| AC Coupled | 10 Hz to >= 125 MHz. |
| Rear Interface |
| DC Coupled | 0 Hz to >= 50 MHz. |
| AC Coupled | 10 Hz to >= 50 MHz. |
| Input Sensitivity |
| X1 Attenuation | 20 mV rms sine wave to 100 MHz.
35 mV rms sine wave to 125 MHz.
60 mV peak-to-peak pulse at a minimum pulse width of 5 ns to 100 MHz.
100 mV peak-to-peak pulse at a minimum pulse width of 4 ns to 125 MHz. |
| X5 Attenuation Accuracy | | <= 2% at dc. |
| Input Dynamic Range |
| X1 Attenuation | | <= 3V, peak-to-peak |
| X5 Attenuation | | <= 15V, peak-to-peak |
| Shaped Outputs |
| Delay From Front Panel | | Typically 15 ns. |
| Output Voltage Levels | | >= 100 mV into 50 Ω, >= 200 mV unterminated. |
| Trigger Level |
| Range | ± 3.5 V times attenuation |
| Slope | Plus (+) or minus (-) | Independently selectable. |
| Output Accuracy | ± 20 mV ± 0.5% of reading |
| Input Impedance |
| Front Panel |
| X1, X5 Attenuation | | 1 MΩ, shunted by approximately 27 pf.
(-13V <= Vin <= +6V). |
| Rear Panel |
| X1, X5 Attenuation | | Approximately 50 Ω at dc. |
| FUNCTIONS |
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| FREQUENCY A |
| Range |
| DC Coupled | DC to 125 MHz |
| AC Coupled | 10 Hz to 125 MHz |
| Minimum Pulse Width | 4 ns at 100 mV, peak-to-peak |
| Accuracy | | ± 1 count ± time base error. |
| Gate Time (Resolution) | | 10 sec to 100 ns (0.1 Hz to 10 MHz) selected in decade steps. |
| PERIOD B (Single Shot) |
| Repetition Rate | >=125 MHz |
| Minimum Pulse Width | 4 ns at 100 mV, peak-to-peak |
| Accuracy | | ± 1 count ± time base error.
± 1.4 X CH B trigger error. |
| Resolution (Clock Rate) | | 10 sec to 100 ns (0.1 Hz to 10 MHz), selected in decade steps. |
| PERIOD B (Average) |
| Repetition Rate | >=125 MHz |
| Minimum Pulse Width | 4 ns at 100 mV, peak-to-peak |
| Clock Rate | | 100 ns (10 MHz), fixed. |
| Number of Averages (N) | | 1 to 10^8, selected in decade steps. |
| Resolution | | 1 femtosecond (10^-15) to 100 ns, selected in decade steps. |
| WIDTH B (Single Shot) |
| Minimum Pulse Width | 10 ns. |
Resolution
(Clock Rate) | | 10 sec to 100 ns (0.1 Hz to 10 MHz), selected in decade steps. |
| WIDTH B (Average) |
| Minimum Pulse Width | 5 ns. |
| Repetition Rate | >=100 MHz |
| Minimum Dead Time | | 5 ns. |
| Clock Rate | | 100ns (10 MHz), fixed |
| Number of Averages (N) | | 1 to 10^8, selected in decade steps. | ,/tr>
| Resolution | | 100 ns / sqrt(N) |
| Time A - B (Single Shot) |
| Minimum Time Interval | 12.5 ns. |
| Resolution (Clock Rate) | | 10sec to 100 ns (0.1 Hz to 10 MHz), selected in decade steps. |
| Time A - B (Average) |
| Minimum Time Interval | 12.5 ns. |
| Minimum Dead Time | | 12.5 ns. |
| Number of Averages (N) | | 1 to 10^8, selected in decade steps. |
| Clock Rate | | 100 ns (10 MHz) fixed |
| Resolution | | 100 ns / sqrt(N) |
| EVENTS A DURING B (Average) |
| Maximum CH A Frequency | >=125 MHz. |
| Minimum CH B Pulse Width | 5 ns |
| Minimum Dead Time Between Pulses | | 5 ns. |
| Number of Averages (N) | | 1 to 10^8, selected in decade steps. |
| RATIO A/B (Average) |
| Frequency Range | >=12 MHz | Both channels. |
| Minimum Pulse Width | 4 ns at 100 mV, peak-to-peak | Both channels. |
| Number of Averages (N) | | 1 to 10^8, selected in decade steps. |
| TOTALIZE A |
| Frequency Range | DC to 125 MHz. | Start/Stop function from front panel or rear interface. Overflows with >99,999,999 counts. |
| TIME MANUAL |
| Clock Rate (Resolution) | | 10 sec to 100 ns (0.1 Hz to 10 MHz), selected in decade steps. |
| Range | | 100 ns to 10^9 sec. Start/Stop function from front panel or rear interface. |
| INTERNAL TIME BASES |
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| Standard Time Base |
| Frequency | 10 MHz (100 ns). | Adjustable to ± 1 part in 10^7, or better. |
| Temperature Stability | | ± 5 ppm. |
| Aging | | <= 1 ppm/year |
| Option 01 Time Base |
| Frequency | 10 MHz (100 ns). | Adjustable to ± 2 parts in 10^8, or better |
| Temperature Stability | | ± 0.2 ppm of final frequency in less than 10 minutes when cold started at 25° C ambient |
| Aging | | < 1 ppm/year. |
above excerpt from DC 503A UNIVERSAL COUNTER Instruction Manual
A brief description of the front panel controls follows.
Because the Channel A and Channel B controls are identical, only Channel a will be described
| DISPLAY AND UNIT INDICATORS |
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| DISPLAY READOUT | Eight-digit, seven segment LED readout with automatically positioned decimal point. |
| OVERFLOW | When illuminated indicates register overflow. |
| GATE | Indicates the state of the main gate. When lit, the main gate is open (the DC 503A is in the process of making a measurement). When the light is off, the gate is closed. |
| GHz/nSEC | When illuminated, indicates the displayed number is gigahertz (GHz) in FREQ A mode or nanoseconds (nSEC) in a time mode. |
| MHz/μSEC | When illuminated, indicates the displayed number is Megahertz (MHz) in FREQ A mode or in microseconds (μSEC) in a time mode. |
| kHz/mSEC | When illuminated, indicates the displayed number is kilohertz (kHz) in FREQ A mode or milliseconds (mSEC) in a time mode. |
| Hz/SEC | When illuminated, indicates the displayed number is Hertz (Hz) in FREQ A mode or seconds (SEC) in a time mode. |
| MODE SELECTION AND CONTROL FUNCTIONS |
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| FUNCTION | Selects the measurement, events, or time counting modes for the counter.
The TOTALIZE A/TIME MANUAL position is an "either/or" function. TOTALIZE A or TIME MANUAL is selected and set by positioning an internal jumper. |
| AVGS/TIMING | Depending on the position of the FUNCTION switch, this switch selects the clock rate which will be counted or the number of measurements to be averaged. |
| DISPLAY TIME | Sets the length of time the reading will be displayed after the count is made and before the next measurement is taken. Display time can be varied from about 0.1 second, fully counterclockwise (ccw), to about 10 seconds fully clockwise(cw). The HOLD position provides continuous display until reset by pushing the RESET button. |
| RESET | Momentary switch resets the count to zero when operating in the TOTALIZE A mode. Also acts as a master reset, ensuring that the readout has been cleared before the next measurement. Provides a check of all display LED's; when pressed, a row of 8's will be displayed in the readout window. |
| START/STOP | Push-Push switch acts as a manual gate when the FUNCTION switch is in the TOTALIZE A/TIME MANUAL position. Button in Starts the measurement interval gate; button out terminates the gate. |
| CHANNEL A INPUT AND LEVEL FUNCTIONS |
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| CH A INPUT | BNC connector for Channel A signal input. Input impedance is 1 MΩ shunted by approximately 20 pF. |
| LEVEL | Selects the amplitude point on the positive or negative slope of the input signal at which the triggering window is placed. |
| SLOPE | Push-Push switch selects the slope of the input signal on which triggering will occur. Button out selects plus (+) slope; button in minus (-) slope. |
| ATTEN | Push-Push switch selects X1 (button out) or X5 (button in) attenuation of the input signal. |
| COUPL | Push-Push switch selects DC (button out) or AC (button in) coupling of the input signal to the attenuator circuit. |
| SOURCE | Push-Push switch selects the source of the input signal. Button out, EXT, selects the front panel connector as a signal source. Button in, INT, routes the input signal to the counter via the rear interface connections. |
| SHAPED OUT A | Provides a shaped output signal derived from the output of the Channel A signal shaper circuitry |
| SHAPED OUT GND | Common connector for Channel A shaped output signals. |
| TRIG LEVEL A | Pin jack permits monitoring of the Channel A triggering voltage level. |
above excerpt from DC 503A UNIVERSAL COUNTER Instruction Manual
| Knobs |
| 1-4 | 366-0494-05 | Knob : Gray (LEVEL) |
| 1-3 | 366-1023-07 | Knob : Gray (DISPLAY TIME) |
| Pots/Switches |
| 1-5 (R500,R600) | 311-2095-00 | Res, Var, Nonwir, 10K 10% 12697 (Clarostat 388) (LEVEL) |
| 1-70 (A14R1410) | 311-2096-00 | Res, Var, Nonwir, 1M Ohm 0.5W 12697 )Clarostat 388) (DISPLAY TIME) |
| 1-70 (A14S1410) | | Part of A14R1410 |
| A12S1810 | 263-0074-00 | Sw, Lever Assy FUNCTION |
| A14S1010 | 263-0074-00 | Sw, Lever Assy TIMING |
| A12S1730 | 263-0010-00 | Switch, PB, 1 Push ATTEN X1/X5 |
| A12S1731 | 263-0010-00 | Switch, PB, 1 Push DC/AC |
| A12S1732 | 263-0010-00 | Switch, PB, 1 Push EXT/INT |
| A12S1720 | 263-0010-00 | Switch, PB, 1 Push SLOPE |
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