DC505

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Tektronix DC505
225 MHz counter/timer
Tektronix DC505

Produced from 1974 to 1976

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

The Tektronix DC505 is a 225 MHz counter/timer plug-in for the TM500 system.

It was superseded by the DC505A in 1976.

Key Specifications

Frequency range 0 Hz (DC coupled) / 10 Hz (AC coupled) to 225 MHz
Sensitivity 50 mVRMS to 150 MHz, 100 mVRMS to 225 MHz (sine)
Resolution 7 digits
Gate time 0.01 s to 10 s in decade steps
Stability Standard: 1×10−5; Opt.1: 5×10−7 (0°C to +50°C, after 30 min warm-up)
Long-term drift Standard: 1×10−5 per month; Opt.1: 5×10−7 per month
Features
  • Two input channels (BNC connectors)
  • Functions: Frequency, frequency ratio, period, interval, pulse width, events
Options
  • Opt.1: 5 MHz TCXO (with ÷5 divider)

Links

Documents Referencing DC505

Document Class Title Authors Year Links
070-2088-00.pdf Book TM500 Series Rear Interface Data Book 1975
070-2088-01.pdf Book TM500 Series Rear Interface Data Book 1976

Rear Interface

Connector Pin Signal Connector Pin Signal
27A Internal Scan Clock Disable
26B Manual Start-Stop 26A /RESET
25B Internal Scan Clock Out 25A Time Slot Zero
24B Internal Scan Clock Out
23B Overflow
21B BCD output 2
20B BCD output 8 20A BCD output 4
19B Data Good 19A BCD output 1
14A Ext Clock Input
Int 1 MHz out via 200 Ω

Data is output serially by digit.

Internals

An internal VCO, phase-locked to the 1 MHz master, produces a 100 MHz input to the counter chain for timing measurements.

The DC505 uses a mix of ECL and TTL dividers and logic, and a Mostek MK5007 four-decade counter/latch/multiplexer (U700). Unlike the similarly-specified 7D15, it employs no Tek made custom ICs. The first counter decade is implemented as a divide-by-2 ECL flip-flop (U342, MC1670) followed by a five-stage ring counter made with MC10131 ECL flipflops, and some logic to BCD-encode the count result. A similar circuit exists in the reference divider chain.

In the power supply, a 723 regulator provides +5 V from the 17.5 VAC mainframe rails using the mainframe's NPN pass transistor. Its output includes a zener/SCR crowbar circuit. Another 723 provides +15 V from the +33 V rail. A discrete regulator using the PNP pass transistor produces –10 V from the –33 V rail.

Pictures

Better pictures needed - please contribute

Components

Some Parts Used in the DC505

Part Part Number(s) Class Description Used in
2N4249 151-0342-00 Discrete component PNP Si low noise amp. DC501 DC502 DC503 DC503A DC504 DC504A DC505 DC505A DC508 DC508A DC509 DC510
Mostek MK5007 156-0409-00 Monolithic integrated circuit four-decade BCD counter with latches and output multiplexer 213 DC505 DC505A