These tubes are the last of their kind, when they're GONE, only the people I sold them to will have them:
They were specially made for the US Navy to hunt down subs in the 60s they were dropped from 500 feet to 5,000 feet, with 80 g shock, then they sunk down about 10 feet propped up the hydrophones were ejected the lead weight fell out and a dye maker was released. Salt water came in and made the special batteries active, they were made to take a depth charge to go off 50 feet away, basically their brick sh*t houses in the 12AX7 WORLD. Google Sonobuoys
I was a young tech then, and we lost the contract for one reason when we converted them to a transistor model, we could not get the second harmonic in the RF stage down to meet the Navy specs sad, we closed up, and I took the tubes, to add to my huge tube collection. I'm now 76 and can use the cash, before I become worm food, bring your own tube checker don't trust mine, 10 for $200 under that's $25 each. The price is firm.Or trade for services, let me know what you can offer never know? I fully expect to see them on ebay for double that price, if not more, never had one come back yet.
Gary Diamond
