Stancor HF-67

Stancor HF-67 High-Fidelity Push-Pull Output Transformer (UTC LS-57 Twin)

Up for sale is a Stancor HF-67 high-fidelity output transformer featuring the classic 13-terminal multi-tap layout. Built to elite studio and high-end hi-fi standards, the HF-67 is widely recognized in the vintage audio community as Stancor's equivalent/rebadged twin to the famous UTC Linear Standard LS-57 (Stancor used the "+10" numbering convention for these high-end models, making the LS-57 an HF-67).

This unit is ideal for premium vintage tube amplifier restorations or custom push-pull builds (supporting classic output tubes such as 2A3, 300B, 6L6, 50, etc.).

BENCH TEST VERIFICATION & RESULTS:

This transformer has been thoroughly tested on the bench to confirm 100% electrical integrity, winding balance, and healthy inductive coupling prior to listing.

1. DC Resistance (DCR) & Winding Balance:

Tested with a digital multimeter across all primary paths.

Clean, continuous, and well-balanced readings confirmed from plate terminals (P / P1) to center taps (B).

2. Low-Voltage AC Step-Down & Inductive Coupling Test:

A 12V AC test signal was injected across the primary to safely verify magnetic core efficiency and turns ratio without subjecting vintage insulation to unnecessary high voltage.

Input voltage split evenly across the center taps, and secondary terminals (13 through 18) yielded clean, stepped-down AC output voltages ranging between 2V and 4V AC (depending on tap combination), confirming zero shorted turns and smooth inductive coupling.

3. Insulation & Isolation Integrity:

Primary-to-Core / Ground: Open Circuit (OL) / Infinite resistance verified.

Primary-to-Secondary: Open Circuit (OL) / Zero leakage.

TERMINAL CONFIGURATION:

Primary Side: Marked P, P1, B, B, P1, P, and Ground (GND). Accommodates push-pull plate connections, center taps, and Ultra-Linear / screen options.

Secondary Side: 6-terminal block numbered 13 through 18 for flexible series/parallel strapping (shares the UTC LS-57 terminal architecture for mapping standard speaker loads from 1.2 ohms up to 500 ohms line matching).

4 1/8” x 4 1/8” x 3 1/4”

5.5 lbs.

Condition & Seller Terms:

Tested & Guaranteed Functional on Arrival: This transformer is guaranteed to arrive in the exact functional condition described above (passing all stated DCR and AC turns-ratio tests).

As-Is Due to Age & DIY Use: Because this is a vintage electronic component intended for custom tube amplifier construction/repair, it is sold As-Is, No Returns once installed. The buyer is responsible for proper installation, correct circuit pinouts, and fusing.