DC504

Manuals – Specifications – Links – Pictures

The Tektronix DC504 is an 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It was superseded by the DC504A in 1984.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. 01 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. Other internal switches select an external reference clock, AC vs DC input coupling, and "latch override" where the count is displayed during the gate interval instead of only at the end, which is useful in Totalize mode.

Links

Documents referencing DC504

Patents that may apply to DC504

Rear Interface

28B − Gate Out, Totalize Start/Stop	28A − Hold
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
	17A – Signal Input GND
	16A − Signal input
	15A – External Clock GND
	14A − External Clock

Prices

DC504 Year Catalog price In 2026 dollars 1975 $325 ~$2,000 1978 $450 ~$2,200 1982 $600 ~$2,000

DC504 Opt.01 Year Catalog price In 2026 dollars 1975 $415 ~$2,500 1978 $650 ~$3,200 1982 $800 ~$2,700

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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  internal, component side

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  internal, copper side

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  internal, component side

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  internal, copper side

Components

Some Parts Used in the DC504

Part	Part Number(s)	Class	Description	Used in
2N4249	151-0342-00	Discrete component	Si PNP low-noise transistor	5A18N • DC501 • DC502 • DC503 • DC503A • DC504 • DC504A • DC505 • DC505A • DC508 • DC508A • DC509 • DC510
2N4851	151-0504-00 • 151-0504-01	Discrete component	silicon unijunction transistor	DC501 • DC502 • DC503 • DC503A • DC504 • DC505 • DC505A • DC508 • DC508A • LA501 • R1330 • 212 • 214 • 4002A • 4623 • 4631 • 4632 • 4633A • 4634 • 4701 • 4701R • 670-0696-01 • 670-1274-00 • 670-1981-00 • 670-1981-01 • 7D01 • 7D12 • 7L12
Mostek MK5009	156-0410-00	Monolithic integrated circuit	oscillator/counter	DC504
Signetics 82S90	156-0482-01	Monolithic integrated circuit	85(100) MHz decade counter	DC504