Used Marconi N37 tube, .tested (pictured under test) at very much over new. Tested on my AVO Mark 4. For reference, the AVO actually applies 250-450 plate volts and tests tubes under power unlike other testers. You can then accurately test for shorts, gas, etc. Well Known that tubes can warp and deform when hot/under full voltage...AVO's will pick this up where others will not. Reference for new N37 per avo manual is IA/MA =  50 and Ma/V is 10. This tube pegged my meter and tested at:

Ia/Ma= 110

mA/V= 8

No shorts, gas, insulation issues, or runaway draw.  No boxes....

Ask questions before bidding as sales are final and as is. I expect winner to contact me within 24 hours and have payment here in 7 days,,,,,do not bid if you don't intend to follow through.  I pack well and ship promptly.  I do ship international, but buyer pays duties and fees.  I don't lie on customs forms. Continental us estimated...Hawaii and Alaska are more, please ask.