Product Overview
Motorola 6-185A51 File Card - 6800 Ohm 1/2W Carbon Composition Resistors, 10% Tolerance, 10 Units Unused NOS
Condition
Unused NOS. Ten carbon composition resistors mounted on the original Motorola file card, axial leads intact and taped to card. Card tab markings legible: 6-185A51, stamped code 1200-5. Reverse side printed code 54-84066A05 visible. Brown-bodied resistors with blue-gray-red-silver band configuration. Sourced from an electronics distributor consolidating inventory.
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Product Overview
Motorola 6-185A51 carbon composition resistors, 6800 Ohm (6.8k), 1/2W, 10% tolerance. Packaged in the original Motorola Communications Division resistor file card, 10 units per card. Carbon composition construction - the type widely used in tube-era radios, televisions, and amplifiers through the 1960s.
Key Features
- Resistance: 6800 Ohm (6.8k)
- Power rating: 1/2 Watt (0.5W)
- Tolerance: 10%
- Type: Carbon composition
- Quantity: 10 units per file card
- Manufacturer part number: 6-185A51 (card tab) / 54-84066A05 (reverse)
- Axial leads, brown body, blue-gray-red-silver band configuration
- Original Motorola Communications Division file card packaging
Applications
- Replacing drifted or failed resistors in vintage tube radios while maintaining period-correct carbon composition characteristics
- Restoring guitar amplifiers where carbon comp resistors contribute to the original circuit behavior and sonic signature
- Swapping out components in vintage televisions and communications gear using the correct original part type
- Experimenting with carbon composition noise characteristics in breadboard or perfboard builds where film resistors behave differently
- Adding to a vintage component collection - original Motorola file cards in unused condition are increasingly difficult to find intact
Frequently Asked Questions
Are these carbon composition or carbon film resistors?
Carbon composition. The brown axial-leaded body and band configuration are consistent with carbon composition construction, and the research confirms this type. Carbon film and metal film resistors have different noise and stability characteristics - if period-correctness or carbon comp behavior matters for your project, these are the right type.
Is the full card of 10 resistors included, or just individual units?
The full original Motorola file card with all 10 resistors is included. Leads are intact and taped to the card as originally assembled.
Can these be used in modern circuits, or only vintage equipment?
They will function in any circuit where 6800 Ohm, 1/2W, 10% tolerance is acceptable. For modern precision or low-noise applications, carbon composition is not the preferred type - metal film offers better stability and lower noise. For vintage restoration, tube amp repair, or circuits where carbon comp characteristics are specifically wanted, these are a direct fit.
What does the 10% tolerance mean practically?
The actual resistance of each unit may fall anywhere between 6120 Ohm and 7480 Ohm and still be within spec. For most tube-era circuit applications this is acceptable. For precision voltage dividers or tight-tolerance analog circuits, confirm your design can tolerate this range before ordering.
Sixty years in storage on an original Motorola file card, leads still straight, markings still sharp. Hand one to the iron and it goes right back to work like nothing happened.
