DC504
The Tektronix DC504 is a 80 MHz, 5-digit frequency counter plug-in for the TM500 system.
It was superseded by the DC504A in 1984.
Key Specifications
| Frequency Range | DC (AC coupled: 10 Hz) to at least 80 MHz |
|---|---|
| Sensitivity | 20 mVRMS sine wave below 15 MHz, 35 mVRMS to 50 MHz, derated down to 175 mVRMS at 80 MHz |
| Input impedance | 1 MΩ // 20 pF |
| Trigger Level Range | −1.5 V to +1.5 V |
| Frequency Resolution | kHz ranges: 0.1 Hz; 1 Hz and 10 Hz (7 digit resolution possible in overflow kHz position); MHz ranges: 100 Hz, 1 kHz (9 digit resolution possible in overflow kHz position) |
| Period resolution | ms ranges: 1 µs, 10 µs; s ranges: 10 ms, 1 ms, 0.1 ms |
| Display Time | Variable ~0.1 s ... ~10 s and HOLD mode |
| Standard Time Base | 1 MHz, ±1×10-5 from 0°C to +50°C, ±1×10-5 per month, Adjustable to within 1×10-7 |
| Opt. 1 Time Base | 5 MHz, ±1×10-7 from 0°C to +50°C, ±1×10-7 per month, Adjustable to within 1×10-9 |
An internal "RPM" mode switch stretches gate times sixfold, giving a longest gate time of 1 minute with a display scaled in revolutions per minute.
Rear Interface
- 28A − Hold
- 28B − Gate Out, Totalize Start/Stop
- 27B − Decimal point
- 26A − /Reset
- 25A − TS1 (digit select 1, MSD)
- 24B − Scan clock out
- 24A − TS2 (digit select 2)
- 23B − Overflow
- 23A − TS3 (digit select 3)
- 22A − TS4 (digit select 4)
- 21B − BCD out 2
- 21A − TS5 (digit select 5, LSD)
- 20B − BCD out 8
- 20A − BCD out 4
- 19B − Latch Out (Data Good)
- 19A − BCD out 1
- 16A − Signal input (GND on 17A)
- 14A − External Clock (GND on 15A)
Internals
The DC504 uses a Mostek MK5009P PMOS oscillator/counter IC to control gate times. The first counter stage is a Signetics 82S90 85(100) MHz decade counter, followed by four 7490 decade counters, 7475 latches, and 7401s to multiplex the output/display.
Pictures
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DC504
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DC504
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DC504
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DC504
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DC504
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DC504
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DC504 inside; component side
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DC504 inside; copper side
