600 ohm audio-frequency transformer 600 : 600, Audio isolation transformer 1:1, Center pin unconnected Frequency Range: 50Hz--100KHz AC Impedance Ratio: about 600 : 600 ohm Inductance: about 1.6H Withstand Voltage: 1000V above About the impedance of coupled isolation transformer: This type of transformer is 600:600 ohm audio transformer, 600:600 means that can be used in such a demand, the impedance of 600 ohm refers to the AC impedance, the DC impedance is about 80 - 100 ohm. Unbalanced to balanced conversion. Use for : Telephone audio isolation; Telephone recording box; 1?When Receiving DTMF signal or FSK caller ID, it can be use to isolate the noise. 2?It can be used on Audio or video signal circuit, power amplifier circuit, set-top boxes and other equipment to isolate noise. 3? when we are using the device, such as Home theater, TV set-top boxes, car computer, their audio output often make some AC interference noise, there will be a horn AC noise, the reason is the common-ground. The ground of signal end and the ground of speaker amplifier end exist potential difference, and the AC noise is caused by the connection of both grounds, the better way is to apart them by using 1:1 audio coupling isolation transformer , thereby inhibiting the noise is caused by the common ground, and this kind of isolation has no effect on sound quality. Shipping 1.You can ask the seller about the shipments to other countries or higher quantity. 2.We are always working hard to ensure your package arrives as soon as possible. Please understand that some factors like weather, high postal traffic, and the performance of shipping companies are outside of our control. 3.Usually product Reaches after about 12-45 business days depending on destination.If you have not received your shipment within 45 days from payment, please contact us. We will track the shipment and get back to you as soon as possible with a reply. Refund or resend product will be offered if item still not received. 4.We maintain high standards of excellence and strive for 100% customer satisfaction! Feedback is very important. We ask you contact us immediately BEFORE you give us neutral or negative feedback, so that we can satisfactorily address your concerns.It is impossible to address issues if we do not know about them!