Vintage Ducon Stacked Dual-Concentric Potentiometer
100K Linear / 500K Log Control | Integrated 4-Tag DPST Switch | Vintage NOS
👨🛠️ Bench Verification & Technical Condition
Up for sale is a rare, premium New Old Stock (NOS) vintage late 1960s / early 1970s Ducon Australian-Made coaxial dual-concentric potentiometer with a built-in heavy-duty safety power switch. This highly specialized component features a stacked independent shaft layout, allowing two stacked control knobs to operate entirely distinct circuit paths out of a single mounting hole, while the initial turn acts as the system safety power toggle. Perfect for deep wooden console faceplates or deep-chassis configurations.
- Coaxial Dual-Concentric Design: Features an outer independent 7mm round brass sleeve (with slots/keyway) controlling the front section and an inner 4.9mm brass shaft with a flattened D-edge passing straight through to actuate the rear resistive track independently. The front shaft extension measures 45mm (55mm total including the threaded mounting collar) and can be cut down to size if needed.
- Component Profile Depth: This unit features a total length of 95mm measuring from the very rear tip of the switch contact tags right up to the front edge of the inner D-shaft tip.
- Integrated DPST Power Switch: Heavy-duty 4-contact Double-Pole Single-Throw assembly rated at 2A 250V. Bench-verified as two completely separate, isolated safety loops (Lines 1-2 and 3-4). Clockwise rotation past detent closes/shorts both lines simultaneously.
- Verified Bench Diagnostics: Directly swept and verified with a digital multimeter to guarantee smooth continuity and confirm authentic legacy era-specific operational curves:
- Note* There is no mounting nut and Washer on this item!
🔹 FRONT POT (Legacy Stamp: 347-DUCON-100KA-PDS507):
• Total Track Resistance (Pins 1 to 3): 126.0 kΩ Max (0.2 Ω Minimum Floor)
• 50% Mechanical Midpoint: Registers at 62.5 kΩ (Confirming a perfect vintage "A" Linear curve)
🔹 REAR POT (Legacy Stamp: 347-DUCON500KC):
• Total Track Resistance (Pins 1 to 3): 506.0 kΩ Max (Confirming an exceptionally tight 500k Nominal range)
• 50% Mechanical Midpoint: Registers a clean legacy "C" Audio Log curve sweep at 62.3 kΩ (~12.3% of total range)
🔹 INTEGRATED SAFETY ROTARY SWITCH:
• Configuration: Heavy-Duty 4-Terminal DPST Array (Rated 2A 250V)
• Operation: Clockwise rotation past detent closes/shorts independent poles (1-2 and 3-4) simultaneously
📊 Stamped Component Specifications
| Brand / Manufacturer | Ducon (Made in Australia) |
| Front Casing Stamp | 347-DUCON-100KA-PDS507 (126.0 kΩ Measured Total) |
| Rear Casing Stamp | 347-DUCON500KC (506.0 kΩ Measured Total) |
| Architecture Layout | Dual-Ganged Concentric Independent Potentiometers + Rear Switch Assembly |
| Taper Profiles (Legacy System) | Front Track: "A" Linear Curve Profile | Rear Track: "C" Log Audio Profile |
| Switch Type | 4-Contact DPST Power Switch Assembly (2A 250V) |
| Terminal Architecture | 3-Pin Hollow Solder Lugs (Front Pot) | 3-Pin Hollow Solder Lugs (Rear Pot) | 4 Switch Tags |
| Total Shaft Dimensions | 45mm Visible Shaft Length (55mm Including Threaded Mounting Collar) |
| Total Component Profile | 95mm Total Length (From switch tag edge to front inner shaft tip) |
| Shaft Diameters & Materials | Solid Brass Coaxial Setup | Outer Sleeve: 7mm Round Slotted | Inner Shaft: 4.9mm D-Profile |
| Era & Origin / Condition | Classic Vintage Stock | Made in Australia | New Old Stock (NOS) |
📻 Historic Radio, TV & Guitar Amplifier Restoration Focus
This highly specific dual-value coaxial component is crucial for period-correct bench work:
- Vintage Audio Gear & Guitar Amplifiers: Known compatible match and excellent restoration stock replacement for vintage Australian and international gear, including classic **Diason, Peavey, Astor, and AWA** valve layouts.
- Classic Valve Radios & Early TVs: Highly targeted for dual circuit adjustments running out of a single faceplate opening while managing safe, isolated high-voltage power entries.
📮 Combined Shipping Policy
Clearing out multiple vintage assets from your workspace project bins? I will gladly manually combine shipping costs across all active listings to save you money on postage. Please add your items to your cart and request a final total before making your payment so I can issue an adjusted invoice based on the true package size and weight.
⚠️ Vintage Electronics Disclaimer
This item is a premium New Old Stock (NOS) component from an accumulation of classic workshop stock. While it has been cleanly bench-tested to confirm precise track resistance, switch continuity, and smooth tracking, vintage electrical hardware components are sold as-is without modern commercial warranties. Please review all dimensions and chassis shaft profiles closely before purchasing.