We have here a pre 1920 , wartime DeForest tube from the very first factory in NY. From the man & company that invented the first triode during the turn of last century. By the time World War I broke out, the earliest receivers used these tubes. The most common model of receiver tube, The Western Electric "VT-1" or vacuum tube #1, was in use all over the USA and Europe. By WWI DeForest had become far overshadowed by WE and GE/Westinghouse in production of the very first triodes. The VT-21 is quite rare  -- they were produced in far lower numbers and consequently far more collectable! 

TheDeForest model VT-21 triode from the mid to late teens of the last century. With a brilliant and clear glass envelope, It has the signature pre 1920's style, (100 year old looking) glass tip --- excellent shape and ever present. This along with the original engraved, still tight nickle base.

It's in excellent shape, save for markings etched on the bottom by some previous owner -- years and years ago I'm sure. 

It's filament seems like it may be open -- making this a display tube. I may not have found the correct connections, so I will leave the remainder investigation to the new owner. I found NO shorts either --  (see photo B). Function not tested, as I don't have a pin adapter setup. The tube looks fine and clearly has an excellent vacuum (glass is crystal clear as you can see). The internal elements of the tube shine brilliantly, including the VT21's somewhat unique ladder style grid. The nickle base is all original with an ancient patina.

For those seeking more info on this rare device, check the two bibles on collector tubes/valves... "70 years of vacuum Tubes" where it's chronicled in the first chapter, and of course "Vacuum Tube Saga".  

Western Electric VT-1's are by comparison quite common. As are the later GE/Westinghouse made RCA RadioTron UX series tubes. Of early collectibles -- DeForest tubes are the ones to seek.

It's quite sobering to realize every person involved in design and manufacture and operation is long gone.

Now a nearly century old and a statement to the amazing quality of early american manufacturing.
Early on, after inventing the Triode, the tube with the first third element... the "grid" -- DeForest set about further refining early triodes for radio receiving and audio amplification.

Deforest made the VT-21 from the 1910s thru sometime just after WW1, where they were used in early radio voice, music and time receivers.
The VT-21 was designed and solely produced by DeForest. What that all means...is that this a very uncommon, rarely seen and highly collectible triode.

Early tubes like this are a sight to be seen and an experience to behold. The incredibly thick glass is much clearer than modern design tubes. They had not yet invented the flash-over process, relying solely on the deep vacuum to allow the tube to function efficiently.

These old VT-21 are seldom seen, even here on EBay. This one presents beautifully and will be a joy to added to your collection.  This may be the only one you see for sale for a long, long time -- and and will sell quickly to a collector. Buy Now to avoid a bidders's war. 

The documents shown in photos are included.