On eBay Now...

Vintage University BR-8 AC Bridge Tester Working 1975 Bench Calibration Graph For Sale

Vintage University BR-8 AC Bridge Tester Working 1975 Bench Calibration Graph
When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Buy Now

Vintage University BR-8 AC Bridge Tester Working 1975 Bench Calibration Graph:
$191.21

Vintage University BR-8 AC Bridge Impedance Tester – Fully Tested & Working


​Up for sale is a spectacular piece of electronic laboratory history: a University Model BR-8 AC Bridge, originally distributed by the Graham Instrument Co. out of Sydney. This alternating current impedance bridge is designed to precisely measure resistance (R), capacitance (C), inductance (L), and transformer turn ratios (T) by balancing decade selector networks against an analog null meter.


​Tested, Working, and Responsive:

​Completely Operational: This unit is verified Tested & Working.


​Active Meter Response: As clearly shown in the listing photographs, the internal circuitry is live, fully responsive, and the analog needle reacts cleanly to circuit balancing and component inputs.


​Smooth Controls: All three upper decade selector knobs, the function selector, the range selector matrix, and the sensitivity dials turn smoothly with crisp mechanical detents.


​Incredible Technical Provenance & Lab Formulas:

​This unit features exceptional "living history" from a dedicated lab technician who relied heavily on this piece of gear, making it a unique standout for collectors or active benches:


Hand-Drawn Calibration Graph: Firmly taped to the rear of the unit is a beautifully detailed, hand-drawn calibration graph completely drafted on graph paper, dated 12-6-75, and signed by the technician ("RHS"). It features a custom schematic circuit diagram for the reference arm (mapping a 0.100\mu\text{F} capacitor, series/parallel switch, and a variable resistor reference arm) plotted against a linear "Loss Balance" reading


Side-Panel Calculation Formula: Features a vintage, hand-inked grid label providing the specific operational formula for calculating internal loss resistance (R_X) relative to a transformer resistance (R_T):


Unit Markings: Hand-marked "RHS SMALL" on the front lip edge, identifying its original dedicated lab bench station.


Condition Notes

​Functional: Excellent working condition. The unit balances and registers actively.

​Cosmetic: Great vintage cosmetic condition with classic mid-century teal-gray hammertone metal finish. Shows light edge wear and minor scuffs from authentic lab bench use. All original faceplate text, the range matrix chart, and the original distributor shield label are beautifully preserved and perfectly legible.


Buy Now

Popular

Recent Posts