Transistor AF178 PNP, Germanium TO-72

Transistor AF178 PNP, Germanium TO-72

Transistor AF178 PNP, Germanium TO-72

Transistor AF178 PNP, Germanium TO-72

Transistor AF178 PNP, Germanium TO-72

Transistors

Reference: TRAF178

Part.No: AF178

€1.59

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The AF178 is a PNP germanium transistor in a TO-72 package with a grounded case lead. Purpose-built for VHF/UHF oscillators, mixers and RF amplifiers in vintage radio and television receivers.

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Description
Product Details

AF178 Germanium PNP Transistor – VHF/UHF RF Oscillators & Mixers

The AF178 is a vintage PNP germanium transistor optimized for RF and VHF/UHF applications. Its four-pin TO-72 package includes a dedicated shield lead that reduces electromagnetic interference, making it ideal for radio tuners, image mixers and crystal oscillators in classic receiver designs.

Functions & Applications

Germanium Construction: Lower forward voltage drop (0.2–0.3V) compared to silicon, beneficial for RF gain and noise performance.
Shielded TO-72 Package: Four-lead design with dedicated ground shield to suppress parasitic oscillations and electromagnetic interference at high frequencies.
VHF/UHF Coverage: Optimized for oscillator and mixer use across VHF and low-UHF television and radio bands.
Vintage/NOS Stock: Original production part suitable for restoration and period-correct repairs of classic receivers.

Technical Specifications

Parameter	Value / Specification
Transistor Type	BJT (Bipolar Junction Transistor)
Polarity / Channel	PNP
Package / Case	TO-72
Transistor Material	Germanium
Package Type	TO-72 (4-pin with shield lead)
Primary Application	VHF/UHF RF Oscillators, Mixers

Frequently Asked Questions

Q: What happens if I don't ground the 4th shield lead on the AF178?
A: At VHF/UHF frequencies, the ungrounded shield can permit parasitic oscillations, causing audible squealing and circuit instability. Always ground the case lead for stable operation.

Q: Is the AF178 suitable for modern DIY projects?
A: The AF178 is primarily a vintage part for restoration and period-correct radio/TV repair. For new designs, modern RF transistors (silicon BJTs or MOSFETs) are preferred, though the AF178 remains valuable for hobbyists building replica VHF/UHF circuits or experimenting with classic receiver designs.

Notes

Vintage germanium transistor, NOS (New Old Stock). Four-pin TO-72 package includes dedicated electromagnetic shield lead. Requires grounding at high frequencies to prevent parasitic oscillations. Non-critical specs (Vceo, Ic, hFE) vary by vintage production batch; cross-reference equivalent period datasheets for exact operating conditions.

Note: Price refers to one (1) piece. The component is shipped in bulk without individual packaging.

Transistor Type: BJT (Bipolar Junction Transistor)
Transistor Polarity / Channel: PNP
Transistor Case Style: TO-72

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