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Tektronix DC502
550 MHz frequency counter
Tektronix DC502

Produced from 1972 to 1977

(All manuals in PDF format unless noted otherwise)
Manuals – Specifications – Links – Pictures

The Tektronix DC502 is a 550 MHz frequency counter plug-in for the TM500 system.

It measures frequencies from 10 Hz to 550 MHz or totalizes events up to the readout capacity of 107-1 at the maximum rate of 550 MHz.


  • Direct Counting to 110 MHz
  • 7 Digit LED Display
  • Manual Start/Stop (Totalize)
  • Gate times: 0.01 s, 0.1 s, 1.0 s, and 10 s
    • Frequency range: 10 Hz to 110 MHz
    • Input impedance: 1 MΩ
    • Sensitivity: 300 mVp-p (100 mVrms sine wave)
    • adjustable trigger level range
    • Frequency range: 50 MHz to 550 MHz
    • Sensitivity: 500 mVp-p (170 mVrms sine wave)
    • Input impedance: 50 Ω

The manual totalizing mode with front panel start stop control is available in both inputs; from the prescale input, 1 displayed count per 10 input events will result.

Measurement display is accomplished with 7 segment LEDs in a seven digit readout. The decimal point is automatically positioned by the measurement interval selected, and leading zeroes (those to the left of the most sig digit or those to the left of the decimal point) are blanked.

LEDs indicate when the gate is armed, and whether displayed numbers are in kHz or MHz, and when register overflow occurs.

A standard internal 1 MHz clock is provided with 1 × 10-5 (10 ppm) stability, but an "Option 01" 5 MHz clock is also available which provides 5 × 10-7 (0.5 ppm) stability. That option includes additional circuitry to divide the clock frequency by 5 in order to obtain 1 MHz.