A86A line matching transformer terminal numbers

FAQ #513 Updated July 18, 2007

Question:

HI. I have an old line matching transformer Shure Mod# A86A. Can't find it in your old product listing. I am trying to put a system back into operation in our Church. I need to know what the terminal numbers mean so that I can hook it up correctly. Any other info you can find would be helpful.

Answer:

The A86A transformer was introduced in 1951. The four pin connector is the low impedance side. Pins 1 and 2 are one of the two primary windings; the impedance is 35 to 50 ohms. Pins 3 and 4 are the other primary winding; the impedance is 150 to 250 ohms.

The two pin connector is the high impedance side. Pins 5 and 6 are the high impedance winding (20,000 to 25,000 ohms). Go from the low side to the high side will provide about 20 dB of gain.

Use the A86A to connect the balanced, low impedance output of a typical "modern" microphone into the high impedance input of a typical "antique" audio mixer/amplifier.

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