Mullard The Fisher ECC83 12AX7 Vintage 1964 i63 Audio Tube Pair (test OK)

They feature a 1964 date code of "B4H2" with gray plates and a round getter. Both are test well and above the minimum. Audio Preamp Tubes (12AX7, 12AY7, 6SN7, 6DJ8, etc). It tests for heater-cathode leakage, gas, mutual conductance, and plate current.

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