DC503

Manuals – Specifications – Links – Pictures

The Tektronix DC503 is a 100 MHz, 7-digit frequency counter plug-in for the TM500 system.

Opt.01 is an OCXO for improved stability.

DC503

Key Specifications

Frequency Range	0.1 Hz (AC coupled: 10 Hz) to 100 MHz
Impedance	1 MΩ paralleled by approx. 20 pF
Sensitivity	300 mVp-p sinewave times attenuation to 100 MHz
Max Input Voltage	1× Atten: 50 V @ ≤2 kHz, derate −20 dB/decade to 10 MHz; 10 V @ 10 kHz to 25 MHz, derate −20 dB/decade to 50 MHz; 5 V @ 50 MHz to 100 MHz
Max Input Voltage	10×/100× Atten: 500 V @ ≤2 MHz, derate -20 dB/decade to 100 MHz
	— Standard time base —
Frequency	1 MHz ± 1 × 10-7 at cal
Error	≤ ±1 × 10-5 from 0 °C to +50 °C
Aging	≤ ±1 × 10-5 per month
	— Opt.01 OCXO time base —
Frequency	5 MHz ± 5 × 10-9 at cal
Error	≤ ±5 × 10-7 from 0 °C to +50 °C (after oven warm-up)
Aging	≤ ±1 × 10-7 per month

DC503A

Key Specifications

Frequency Range	0 Hz (AC coupled: 10 Hz) to ≥125 MHz
Impedance	1 MΩ paralleled by approx. 27pF
Sensitivity	20 mVRMS sinewave to 100 MHz, 35 mVRMS sinewave to 125 MHz
Max Input Voltage	1× Atten: 200 Vpeak, 400 Vp-p @ DC − 50 kHz; 200 Vpeak, ≤(20/f) Vp-p @ 50 kHz − 1.33 MHz; 200 Vpeak, ≤15 Vp-p @ 1.33 – 125 MHz
Max Input Voltage	5× Atten: 200 Vpeak, 400 Vp-p @ DC − 5 MHz; 200 Vpeak, ≤(2000/f) Vp-p @ 5 − 100 MHz; 200 Vpeak, ≤20 Vp-p @ 100 – 125 MHz

Gerbers

• Divide-by-5 circuit board gerbers 670-3300-00 (ZIP)

Rear interface DC503 (non A)

• 14A − 1 MHz clock out
• 16A − CH A input (GND return on 17A)
• 17B − CH B input (GND return on 16B)
• 19B − Data good
• 19A − BCD output serial-by-digit (1)
• 20A − BCD output serial-by-digit (4)
• 20B − BCD output serial-by-digit (8)
• 21B − BCD output serial-by-digit (2)
• 22B/23B − Overflow out/overflow display disable in
• 24B/25B − Internal scan clock out/external scan clock in
• 25A − Time slot zero (TS₀)
• 26A − Reset, in/out
• 27A − Internal scan clock disable

Links

• Tektronix DC503A Frequency Counter OCXO Mod by NFM @ YouTube

Pictures

DC503

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  DC503

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  DC503

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  DC503

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  DC503 and PG502 in a TM503

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  DC503

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  DC503

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  DC503

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  DC503

DC503A

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  DC503A

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  DC503A

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  DC503A left internal