New old stock Raytheon 1960's vintage US made military issue 5678 tubes. This is a low voltage (operates on as little as 45 volts DC plate/anode voltage, so could operate directly off 48 volt phantom power supply lines) subminiature broadband pentode. The filament operates from 1.25 volts at only 50 milliamps, so could be supplied from an ordinary dry cell or alkaline battery.These are from the original factory bulk crates as shown. Offers on this item considered for quantity 50 or more. This item is shipped from Britain, in North America or Asia please allow 2 to 3 weeks for delivery.
You can find data on this tube here: http://www.mif.pg.gda.pl/homepages/frank/sheets/138/5/5678.pdf