QRS Music only made valves for a short time around 1925 and musical instruments was and remains their business. They made a range of valves and it is not clear what Type this is.
The following is from UV201.com:
The QRS Music Company produces and markets mechanical music items, and are best known for player pianos and rolls. The company is still very much alive and concentrating on their traditional market, but for a brief time in the 1920's, they also sold a line of radio tubes.
The QRS tubes were distinctive, to say the least. They were dipped in a clear red lacquer and, appropriately, called Red top tubes. Naturally, this had no effect on their operation, but they look great when they are lit. In the early days of radio, when this technology still had a magic quality about it, appearance was as important as actual performance. The exotic appearance of the QRS tubes, with two red lights burning in each one, must have been very impressive to the gullible customer.
The gettering completely covers the inside of the glass and is opaque - so no red glow from this valve. On the base cap is the locating pin for the UX4 bayonet valve holder.
The base cap and pins. The pins are not split as the twist into the holder pushes the pin into a spring clip.
The wide glass tube envelope is 35 mm in diameter, and excluding the B4 base pins is 91 mm tall.
References: Data-sheet & UV201.com.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated July 06, 2021.