ZXY-3108 12:1 Audio Isolation Transformer - 140 kOhm Permalloy Core | Mu-Metal Shielded | Vertical 4+4 Pin Through-Hole | Hi-Fi Valve Amplifier

1. Product Overview

The ZXY-3108 is a 12:1 audio isolation transformer built on a permalloy core and sealed in a mu-metal case. It combines a 140 kOhm primary impedance with a 12:1 (N1:N2) turns ratio to provide galvanic isolation and effective common-mode noise rejection in high-impedance, high-fidelity audio signal paths. The unit is supplied as a 31.0 mm x 22.0 mm vertical-mount body with a 4 + 4 pin arrangement for through-hole PCB layouts.

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

General information

Item	Specification
Model	ZXY-3108 (12:1 turns ratio)
Our 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 is finished in satin metal with a printed identification label on the top face, on which pin 1 is marked with a white dot. The nameplate identifies the model, the 12:1 ratio and the pin 1 position, which helps to avoid wiring errors during assembly and field service.

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

2. Features

• Turns ratio (N1:N2) — 12:1 ±2% at 20 kHz, 1 V.
• Impedance — 140 kΩ ±10% 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 — Between the primary and secondary windings, brought out on pin 2.
• Permalloy core — Mu-metal case for magnetic shielding (pins 3 and 6).
• Insulation and wire — Interleaved insulation of 2 layers; primary wire 2UEW-F 0.045 mm x 1P, secondary 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 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 mu-metal case.

3. Advantages

The permalloy (high-permeability nickel-iron) core and the mu-metal case give the ZXY-3108 high primary inductance together with effective magnetic shielding. The result is low insertion loss, low distortion and a wide, even frequency response, with strong suppression of common-mode noise picked up along the signal cable.

Two-layer interleaved insulation and an electrostatic shield between the windings reduce capacitive coupling and keep the 12:1 ratio consistent from unit to unit, while the step-down ratio matches high-impedance valve and tube stages to lower-impedance line inputs. The 31 mm x 22 mm body and 4 + 4 pin pattern save board space and suit automatic insertion, and all wound components are UL-recognised.

Because the windings are wound on the permalloy core and the assembly is epoxy-sealed and varnish-impregnated, electrical performance stays stable within the rated ambient range and the finished part resists moisture, mechanical stress and vibration in transport and in service.

Figure 4 — ZXY3108 12:1 audio isolation units, satin mu-metal case and printed top label.

4. Applications

The ZXY-3108 is designed for signal isolation wherever ground loops or common-mode noise must be removed:

• Hi-fi valve amplifiers — Tube amplifiers, pre-amplifiers and inter-stage coupling.
• Line-level isolation — Line-level isolation and ground-loop breaking in audio systems.
• Balanced-to-unbalanced conversion — Mixers, interfaces and audio processors.
• Instrumentation inputs — Galvanically isolated inputs for instrumentation and professional audio equipment.
• PCB-level isolation — Isolation in measuring, control and communication equipment.

Figure 5 — Isolation transformers in a valve amplifier signal path.

Figure 6 — PCB-level mounting with twisted-pair flying connections.

5. Specifications

Electrical data are specified at 25 °C and follow the customer specification drawing for ZXY3108-12:1, edition A/0. All dimensions are in millimetres; pin numbering is shown viewed from the bottom of the unit.

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
DCR (pins 1-4)	4.6 kΩ ±15%	at 25 °C
DCR (pins 5-8)	62 Ω ±15%	at 25 °C
Hi-Pot (PRI-SEC)	AC 1250 V	1 mA, T = 2 s, AC 50 Hz
Insulation resistance (PRI-SEC)	100 MΩ MIN	DC 500 V

5.2 Construction and Specification

Item	Specification
Core	Permalloy
Construction	Vertical mount, 4 + 4 pins
Primary inductance (1-4)	3990.5 TS
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 TS)
Weight	Approx. 20 g
Operating temperature	-25 °C to +85 °C
RoHS	Compliant

Primary inductance is quoted as 3990.5 TS in the customer specification sheet.

5.3 Mechanical Dimensions (unit: mm)

Dimension	Value
Overall diameter	Ø31.0 ± 1.0
Total height	22.0 ± 1.0
Pin pitch, front view	5.0 ± 0.3
Pin row spacing, side view	12.5 ± 0.5
Pin circle / body diameter	Ø31
Pin arrangement	8 pin positions, 4 + 4, vertical through-hole; pin 7 trimmed as shown in the drawing

Figure 7 — Product views, sealed case construction and pin layout.

5.4 Pin Function

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

Pins 1 and 8 are the dotted (start) terminals. The specification artwork designates the shield, case and core connections E1 (pin 2), E3 (pin 3), E4 (pin 6) and E2 (pin 7). Pin 1 is identified by the white dot on the top label.

5.5 Material List

No.	Description	Specification	UL No.
1	Bobbin	T375HF	E59481
2	Tape	JY-133	E309872
3	Wire	QA-1/155, 2UEW-F	E355168
4	Bar tin	Sn-0.3Ag-0.7Cu	—
5	Core	Permalloy	—
6	Mu-metal case	Permalloy	—
7	Epoxy	FC-500	—
8	Varnish	E962	E335405

6. Quality & Testing Assurance

• Inspection — Every unit is manufactured to specification G2505 and verified against the electrical table: turns ratio, impedance, DCR, dielectric strength (Hi-Pot) and insulation resistance.
• Protection — Windings are interleaved with two insulating layers, epoxy-sealed and varnish-impregnated to protect the assembly against moisture, mechanical stress and vibration.
• UL-recognised components — Bobbin UL E59481, tape UL E309872, wire UL E355168, varnish UL E335405.
• Environmental — RoHS compliant and rated for operation from -25 °C to +85 °C.

The unit is built to the customer specification drawing ZXY3108-12:1 (specification no. 20240424001, edition A/0, dated 24 April 2024), which defines the dimensions, electrical values and material list reproduced in this description.

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