DC503A
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The Tektronix DC503A is a 125 MHz, 8-digit frequency counter plug-in for the TM500 system.
It replaced the DC503 in 1981.
Key Specifications
Resolution | 8 digits |
---|---|
Frequency Range | DC (AC coupled: 10 Hz) to ≥125 MHz |
Impedance | 1 MΩ paralleled by approx. 27 pF |
Sensitivity | 20 mVRMS sine to 100 MHz, 35 mVRMS sine to 125 MHz |
Max Input Voltage | 1× Atten: 200 Vpeak, 400 Vp-p @ DC − 50 kHz; 200 Vpeak, ≤(20/f) Vp-p @ 50 kHz − 1.33 MHz; 200 Vpeak, ≤15 Vp-p @ 1.33 – 125 MHz |
Max Input Voltage | 5× Atten: 200 Vpeak, 400 Vp-p @ DC − 5 MHz; 200 Vpeak, ≤(2000/f) Vp-p @ 5 − 100 MHz; 200 Vpeak, ≤20 Vp-p @ 100 – 125 MHz |
Options
- Opt. 01 — OCXO
Links
- Tektronix DC503A Frequency Counter OCXO Mod by NFM @ YouTube
Documents Referencing DC503A
Rear interface
27B − Decimal point | |
26B – Remote Start | 26A − /Reset |
25A − TS1 (digit select 1, MSD) | |
24B − Scan clock out | |
23B − Overflow | |
22B − Ch.B Level | 22A − Ch.A Level |
21B − BCD out 2 | 21A − TTL Clock Input |
20B − BCD out 8 | 20A − BCD out 4 |
19B − Latch Out (Data Good) | 19A − BCD out 1 |
17B – Ch B Input | 17A – Ch A Input GND |
16B – Ch B Input GND | 16A − Ch A Input |
15B – 10 MHz Ref Out | 15A – Clock GND |
14A − External Clock In |
Internals
The DC503A is implemeted in a mix of ECL, TTL, and MOS ICs. uses an LS7031 6-digit counter IC, and two 74LS288 PROMs that encode decimal point position and annunciators.
Pictures
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DC503A
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DC503A
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DC503A left internal
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right internal
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left internal (Opt.01)
Components
Some Parts Used in the DC503A
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 |