Q: Explain the difference between DC-isolated and non-isolated transformers.

A. A DC-isolated transformer is one that does not allow a DC current to pass between the primary and secondary windings.

Q: Mini-Circuits transformers are tested with 50Ω systems. How do they perform at other impedance?

A. Mini-Circuits’ transformers can be used over a wide range of impedance ranges with an impedance as low as 12.5Ω with a only small change in the bandwidth

Q: Are Mini-Circuits’ transformers step-up or step-down?

A. All Mini-Circuits transformers are specified as step-up transformers. However, they are tested both ways and may be used as a step-up or a step-down.

Q: Can I just use one side of a center-tapped transformer?

A. Yes. You may use one side of the transformer but you should remember you will obtain only one fourth of the impedance ratio.

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Figure 1

Q: Can Mini-Circuits supply MIL-tested transformers?

A. Yes, Mini-Circuits’ hermetically-sealed TMO transformers meet military needs. Please submit your environmental requirements to Mini-Circuits for review.

Q: What are the effects of temperature extremes on Mini-Circuits transformers?

A. The permeability of the core is influenced by temperature. As the temperature decreases, there is a change in the permeability causing an increase in the insertion loss at low frequency.

As temperature increases, the permeability increases thereby slightly decreasing insertion loss at low frequency. This is true, however, as long as the temperature does not increase above the Curie temperature of the core. Mini-Circuits’ designs use cores that have a Curie temperature much higher than the highest specified operating temperature.

Q: Explain the reasons for low-end and high-end losses of a transformer.

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Figure 2

The low-end loss is heavily influenced by the primary inductance while the high-end loss is attributed to the inter-winding capacitance and series inductance.

Q: How do I measure the insertion loss of a transformer?

A. The insertion loss is measured on two transformers connected back-to-back (impedance matched) and dividing the resulting insertion loss by two.

Q: Can I build a power splitter with Mini-Circuits’ transformers?

A. You can use the Mini-Circuits’ T2-1T, to create a 50Ω, 180° power splitter.

The isolation between output ports and the output return loss of each port will not be as good as a MiniCircuits’ standard power splitter.

Q: What are the breakdown voltage ratings of Mini-Circuits’ transformers?

A. Mini-Circuits does not typically specify a break down voltage. However, many of our transformers are able to handle up to 1000 VRMS. Please contact the factory about the transformer of your choice.

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