ZXY-3108 12:1 Audio Isolation Transformer - 140 kOhm Permalloy Core | Mu-Metal Shield | Vertical 4+4-Pin DIP | High-Fidelity Tube Amp

1. Product Overview

The ZXY-3108 is a 12:1 audio isolation transformer manufactured with a permalloy core and sealed within a permalloy shield. It combines a 140 kΩ primary impedance with a 12:1 (N1:N2) turns ratio to provide electrical isolation and effective common-mode noise rejection in high-impedance, high-fidelity audio signal paths. The product features a 31.0 mm x 22.0 mm vertical-mount body with a 4 + 4 pin arrangement, designed for through-hole PCB layouts.

Figure 1 — ZXY-3108 12:1 audio isolation transformer with CCC / CE / RoHS / UL markings.

Basic Information

Item	Specification
Model	ZXY-3108 (12:1 turns ratio)
Manufacturer Part Number	ZXY3108-12:1
Customer Part Number	G2505
Type	Vertical-mount audio isolation transformer, 4 + 4 pins
Manufacturer	Shenzhen ZhiXiangYuan Electronics Co., Ltd.

The body features a satin metal finish with a printed identification label on top, and pin 1 is marked with a white dot. The nameplate indicates the model, 12:1 turns ratio, and pin 1 position, helping to avoid wiring errors during assembly and field maintenance.

Figure 2 — Top view with printed identification label (pin 1 marked) and bottom view showing 4 + 4 pin layout.

2. Product Features

• Turns Ratio (N1:N2) — 12:1 ±2%, tested at 20 kHz, 1 V.
• Impedance — 140 kΩ ±10%, tested at 1 kHz, 1 V, measured with a 1.0 kΩ load.
• Low DC Resistance — 4.6 kΩ ±15% (pins 1-4) and 62 Ω ±15% (pins 5-8).
• Electrostatic Shield — Located between primary and secondary windings, terminated at pin 2.
• Permalloy Core — Permalloy shield provides magnetic shielding (pins 3 and 6).
• Insulation and Magnet Wire — 2 layers of interleaved insulation; primary magnet wire 2UEW-F 0.045 mm x 1P, secondary magnet wire 2UEW-F 0.11 mm x 1P.
• Dielectric Strength — Primary to secondary: AC 1250 V, 1 mA, 2 s, 50 Hz.
• Insulation Resistance — 100 MΩ minimum, tested at DC 500 V.
• Operating Temperature — -25 °C to +85 °C.
• Weight and Compliance — Approx. 20 g; RoHS compliant.

Figure 3 — Vertical-mount construction with sealed permalloy shield.

3. Product Advantages

The permalloy (high-permeability nickel-iron alloy) core and permalloy shield give the ZXY-3108 high primary inductance and effective magnetic shielding performance. This results in low insertion loss, low distortion, and a wide, flat frequency response, while providing strong rejection of common-mode noise picked up on signal cables.

Two layers of interleaved insulation and an electrostatic shield between windings reduce capacitive coupling and ensure batch-to-batch consistency of the 12:1 turns ratio, while the step-down ratio matches high-impedance tube stages to lower-impedance line inputs. The 31 mm x 22 mm body size and 4 + 4 pin arrangement save board space and support automatic insertion, with all winding components UL-recognized.

Since the windings are wound on a permalloy core and the assembly is epoxy-sealed and varnish-impregnated, electrical performance remains stable across the rated ambient temperature range, and the finished product resists moisture, mechanical stress, and vibration during shipping and use.

Figure 4 — ZXY3108 12:1 audio isolation transformer with satin permalloy shield and printed top label.

4. Application Areas

The ZXY-3108 is designed for signal isolation applications requiring elimination of ground loops or common-mode noise:

• High-Fidelity Tube Amplifiers — Tube power amplifiers, preamplifiers, and interstage coupling.
• Line-Level Isolation — Line-level isolation and ground loop breaking in audio systems.
• Balanced-Unbalanced Conversion — Mixing consoles, interfaces, and audio processors.
• Instrument Inputs — Electrically isolated inputs for instruments and professional audio equipment.
• PCB-Level Isolation — Isolation in measurement, control, and communication equipment.

Figure 5 — Isolation transformer in a tube amplifier signal path.

Figure 6 — PCB-level mounting with twisted-pair lead wires.

5. Technical Specifications

Electrical data is specified at 25 °C and follows customer specification drawing ZXY3108-12:1 Rev A/0. All dimensions are in millimeters; pin numbering is viewed from the bottom of the device.

5.1 Electrical Specifications (at 25 °C)

Parameter	Value	Conditions
Impedance	140 kΩ ±10%	1.0 kΩ load, 1 kHz, 1 V
Turns Ratio (N1:N2)	12:1 ±2%	20 kHz, 1 V
DC Resistance (pins 1-4)	4.6 kΩ ±15%	At 25 °C
DC Resistance (pins 5-8)	62 Ω ±15%	At 25 °C
Dielectric Test (Primary-Secondary)	AC 1250 V	1 mA, T = 2 s, AC 50 Hz
Insulation Resistance (Primary-Secondary)	100 MΩ min.	DC 500 V

5.2 Construction and Specifications

Item	Specification
Core	Permalloy
Construction	Vertical mount, 4 + 4 pins
Primary Inductance Turns (1-4)	3990.5 turns
Primary Copper Wire	2UEW-F 0.045 mm x 1P
Secondary Copper Wire	2UEW-F 0.11 mm x 1P
Interleaved Insulation	2 layers (tape, 2 wraps)
Weight	Approx. 20 g
Operating Temperature	-25 °C to +85 °C
RoHS	Compliant

The primary inductance turns are specified as 3990.5 turns in the customer specification.

5.3 Mechanical Dimensions (Unit: mm)

Dimension	Value
Outer Diameter	Ø31.0 ± 1.0
Overall Height	22.0 ± 1.0
Pin Spacing (front view)	5.0 ± 0.3
Row Spacing (side view)	12.5 ± 0.5
Pin Circle / Body Diameter	Ø31
Pin Configuration	8 pin positions, 4 + 4 arrangement, vertical through-hole; pin 7 trimmed as shown in drawing

Figure 7 — Product view, sealed housing construction, and pin layout.

5.4 Pin Functions

Pin	Function
1	N1 start (primary)
2	Shield — E1
3	Metal housing
4	N1 finish (primary)
5	N2 finish (secondary)
6	Core
7	E2 (trimmed as shown in drawing)
8	N2 start (secondary)

Pins 1 and 8 are dot-marked (start) terminals. The specification drawing designates shield, housing, and core connections as E1 (pin 2), E3 (pin 3), E4 (pin 6), and E2 (pin 7), respectively. Pin 1 is identified by a white dot on the top label.

5.5 Bill of Materials

No.	Description	Specification	UL Number
1	Bobbin	T375HF	E59481
2	Tape	JY-133	E309872
3	Magnet Wire	QA-1/155, 2UEW-F	E355168
4	Solder Bar	Sn-0.3Ag-0.7Cu	—
5	Core	Permalloy	—
6	μ-Metal Shield Can	Permalloy	—
7	Epoxy Resin	FC-500	—
8	Insulating Varnish	E962	E335405

6. Quality and Testing Assurance

• Inspection — Every unit is manufactured to G2505 specification and verified against the electrical table: turns ratio, impedance, DC resistance, dielectric strength (hi-pot test), and insulation resistance.
• Protection — Windings are interleaved with two insulation layers, epoxy-sealed, and varnish-impregnated to protect the assembly from moisture, mechanical stress, and vibration.
• UL-Recognized Components — Bobbin UL E59481, tape UL E309872, magnet wire UL E355168, insulating varnish UL E335405.
• Environmental — RoHS compliant, rated operating temperature range of -25 °C to +85 °C.

This device is manufactured in accordance with customer specification drawing ZXY3108-12:1 (specification no. 20240424001, Rev A/0, dated April 24, 2024). The dimensions, electrical values, and bill of materials listed in this description are based on this drawing.

Figure 8 — Specification summary: mechanical dimensions, pin functions, and electrical parameter table.