The DL82 from Osram is a double diode variable μ triode for use as detector, AGC rectifier and first audio voltage amplifier in broadcast superhet receivers. It was first seen at the 1947 Olympia show and was obsolescent by early 1951. The DH81 was similar and pin compatible but had a higher amplification factor and a higher ra but no vari-μ characteristic.
The Osram logo.
The cathode connection is made to the top. The diodes are the small bright cylinders seen below the lower mica.
The carburised anode is stitched together. The grid can be seen above and below the anode. The central cathode tube is oxide coated only where the emissive surface is required.
The wide glass tube envelope is 32 mm in diameter, and excluding the B8B base pins is 56 mm tall.
References: 1040 & 4018. Type DL82 was first introduced in 1947.