The DV-5 was introduced in 1925. This valve was used mainly as an audio amplifier and had higher ratings than the DV-2 that was introduced in 1923. The DV-5 was particularly useful as a driver for an power output valve.
Lee De Forest was the man who introduced the grid first into the valve. This triode was made by his company.
The base has four stub pins and was made of ceramic. Isolantite was the trade name and the manufacturer still exists in America.
A DV-5 was sold on ebay complete with original protective can.
This image of a DV-5 leaflet, found on the internet, gives the basic operating details for the valve.
The wide glass tube envelope is 32 mm in diameter and, excluding the UV base pins the valve is 99 mm long.
References: Bill Condon, data-sheet & 1047. Type DV-5 was first introduced in 1925. See also 1925 adverts.
Updated September 20, 2020.