221

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Tektronix 221
5 MHz miniature analog scope
Tektronix 221

Produced from 1975 to 1991

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

The Tektronix Type 221 is a miniature 5 MHz analog scope introduced in 1973.

Key Specifications

Bandwidth DC to 5 MHz
Input Impedance 1 MΩ // 29 pF
Input Voltage max. 600 V DC + Peak AC, or 600 Vp-p AC
Sweep Range 200 ms to 1 μs, 17 steps
CRT 154-0705-00, 6 Div (V) × 10 Div (H), 1 kV acceleration
Operating Time on Battery 2-3 hours
Internal Battery 10 rechargeable NiCd cells
Line Voltage 90-250 VAC @ 48−62 Hz, or 80-250 VDC
Power Consumption 5 W
Dimensions (H/W/D) 3" × 5.25" × 9" (7.6 cm × 13.2 cm × 22.8 cm)
Weight 3.5 lb (1.5 kg)

Links

Documents Referencing 221

Document Class Title Authors Year Links
60AX-4741.pdf Application Note Floating Oscilloscope Measurements ... And Operator Protection 1981

Prices

Year 1976 1977 1980 1982 1986
Catalog Price $825 $975 $1,325 $1,600 $2,260
In 2023 Dollars $4,500 $5,000 $4,900 $5,100 $6,300

Internals

The 221 has a switching power supply and built-in rechargeable batteries (which are a maintenance issue). The batteries are an integral part of the power supply, which, unmodified, will not perform properly without them.

The power supply in the 221 uses three transformers: 120-0877-00/120-0946-00 (T623) in the base drive for the line inverter, 120-0876-00 (T633) steps down and rectifies the line inverter, and 120-0875-00 (T701) in HV inverter.

The vertical output amplifier that drives the CRT plates is two op-amps made from discrete transistors. One drives the top deflection plate, the other the bottom plate.

The trigger circuit uses a 1N3713 1 mA tunnel diode.

The 221 contains one integrated circuit, a 741 op-amp that creates a virtual ground, otherwise only discrete (including dual) transistors.

MOD 290A is a version of the 221 made for IBM which adds a Single Sweep function and a "Property of IBM" engraving.

Pictures

Internals

Components

Some Parts Used in the 221

Part Part Number(s) Class Description Used in
120-0876-00 120-0876-00 Discrete component pot core transformer 221
154-0705-00 154-0705-00 CRT CRT for miniature scopes 221
2N3958 151-1054-00 151-1054-01 151-1054-02 Discrete component dual n-channel JFET FG503 MR501 M3 PG505 SC501 SC502 SC503 SG502 1450 1501 1502 1503 221 5A23N 5CT1N 577 603 603A 604 604A 605 606 606A 606B 607 607A 620 624 7CT1N 7D15 7D20 851
STD933 152-0181-00 Discrete component 1 mA, 5 pF germanium tunnel diode 1S2 221 422