It's only the Chelmer box, but the pipes from the title are in question.
The Zaerix RS1003, also known as the SRS551, is an air-cooled output pentode intended for high-voltage applications, including operation in radio transmitters or in specialized high-power tube amplifiers. These powerful lamps are characterized by robust construction and reliable operation in demanding conditions, which makes them an interesting choice for enthusiasts and DIYers who want to experiment with high powers and an authentic "old-school" approach to electronics.
Thanks to the quality of construction and precise technical characteristics, Zaerix RS1003 maintains stable performance even when exposed to high voltage and temperature loads. For those planning to build or restore a specialized transmitter or want to take advantage of big tube builds in the audio world, these tubes can provide a stunning combination of raw power and reliability.
