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Tektronix DC501
basic 100 MHz frequency counter
Tektronix DC501

Produced from 1972 to 1980

Manuals – Specifications – Links – Pictures

The Tektronix DC501 is a basic 100 MHz frequency counter plug-in for the TM500 system.

Key Specifications

Input frequency 10 Hz to 100 MHz
Gate time 10 ms to 10 s in decade steps, plus Manual (totalize count of up to 107 events)
Resolution 7 digits
Display 7-digit LED, overflow indicator
Input impedance 1 MΩ // 20 pF, ×5/×10/×50 attenuator (front) or 50 Ω // 20 pF (rear)
Time base stability ≤1×10-5; Opt. 1, ≤5×10-7 (0°C to +50°C after ½h warm-up)
Time base drift ≤1×10-5; Opt. 1, ≤1×10-7 (per month)


  • Option 1 – 5 MHz TCXO with 1:5 divider
  • Option 2 – Automatic Gate Control and Readout Scaling Circuit (automatically selects the 0 .1-, 1-, or 10-second measurement interval to display the largest number of digits without overflow)

Rear Interface

Connector Pin Signal
28B Second decimal point (D2) output
27A Internal scan clock disable input
27B MHz light output
26A Reset input/output
25A TS0 (Time Slot Zero) output
25B External scan clock input
24B Internal scan clock (2 kHz) output
23B Overflow output
22B MSD (most significant digit)
20B 28 BCD output, serial by digit
20A 24 BCD output, serial by digit
21B 22 BCD output, serial by digit
19A 21 BCD output, serial by digit
19B Data Good output
17A Signal input ground
16A Signal input