KT-66 Genalex Tube . Made in England.

• Manufactured at M-O Valve Co. Hammersmith in Nov. 1960.

 TV-7D/U: Tested NOS: 50/ 32 Baseline.

• Brown Bottom
• Power Tube
• Gray Glass

• Date Code: RL Z
• Comes with Original Box 

Testing & Condition

• Minimum reading: 65% (per original 32 baseline; military standard).
• Tubes test NOS and meet or exceed published GM data.
• All tubes tested for gas, shorts, transconductance, and emissions.
• TV-7 tested (calibrated, military-standard tester). 

About NOS & Testing

• NOS tubes fall within the GM range published in the RCA Receiving Tube Manual; variation above/below average is normal.
• No universal test result defines NOS. Typically, NOS tubes measure between average and maximum micromhos.
• Different testers (even identical models) may produce different readings.
• 100% meter readings are not required?passing = meeting spec range or minimum (TV-7: ~65%).
• 12AX7 Minimum Range: 32.
• 12AX7 Nos Range 45 +.