Product Overview
Glass Passivated 800V 8A Bridge Rectifier - KBU 4-Pin Through-Hole, AC to DC Full-Wave, Unused NOS
Condition
Unused NOS. Black flat-pack body marked KBU8K, GI, TAIWAN, and date code 9306. Four leads show light surface oxidation consistent with age - cleans up nicely with a mild citric acid solution. Sourced from an electronics distributor consolidating inventory. Covered by our no-hassle guarantee.
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Product Overview
General Instruments KBU8K - a glass passivated single-phase bridge rectifier in the through-hole KBU 4-pin inline package. Converts AC to full-wave DC at up to 800V peak reverse voltage and 8A average output current. GI was absorbed into Vishay; the KBU8K continues to appear in Vishay's catalog under the same specifications. Date code 9306 places manufacture in early 1994.
Key Features
- Maximum repetitive peak reverse voltage (VRRM): 800V
- Average rectified forward output current (IO): 8.0A with heatsink at TC = 100°C
- Peak forward surge current (IFSM): 300A at 8.3ms single half sine-wave
- Maximum instantaneous forward voltage drop (VF): 1.0V per diode at 8.0A
- Operating temperature range: -55°C to +150°C
- Package: KBU / Through-hole 4-pin SIP - hand-solderable, PCB-mountable
- Glass passivated junction for stable reverse leakage characteristics
- Polarity symbols stamped on front casing face; integral mounting notch
Applications
- Repair technician replacing a failed rectifier in a tube amplifier or high-fidelity audio power supply - desolders the bad bridge, drops this one in, restores DC rail
- Vintage electronics restorer who insists on name-brand GI silicon to keep the build period-correct under the chassis
- Hobbyist winding a custom transformer and building the rectifier stage for a bench power supply or DC motor driver
- Vocational or university lab demonstrating full-wave AC-to-DC rectification on a prototype PCB
- SMPS or monitor repair where the bridge rectifier is the first suspect after a dead power supply diagnosis
- Makers building low-frequency AC power harvesting circuits or variable voltage supplies for motor speed experiments
Frequently Asked Questions
Does this need a heatsink?
At full rated current of 8A, yes - a heatsink is required to maintain junction temperature within spec. The 8A IO rating is specified with a heatsink at TC = 100°C. For lighter loads in free air, derating applies. The integral mounting notch on the body accommodates standard KBU-footprint heatsink clips.
What is the difference between the KBU8K and other KBU8 variants?
The KBU8 series varies only in peak reverse voltage rating. The K suffix designates 800V VRRM. Other variants range from 50V (KBU8A) to 1000V (KBU8M). Current rating, package, and all other specs are shared across the series.
Is it compatible with capacitive filter loads?
Yes, with derating. For capacitive loads, the continuous forward current rating should be derated by 20%, putting the practical limit closer to 6.4A in a typical filtered supply design.
What is included with the order?
The KBU8K rectifier only. No heatsink, hardware, or documentation included.
A GI date code from 1994 on a part that has never seen a circuit board - that is a clean starting point for whatever power supply you are building or bringing back to life. The leads clean up, the junction is intact, and the rest is yours.
