6H6 Variations
12 variations of the 6H6 tube

Photo provided by Robert Deuel

This page was last updated on: March 29, 2013
This photo shows 5 versions of the 6H6 being from left to right as follows:

Zenith 6H6G with "ST" envelope
Sylvania 6H6G with tall T9 envelope
  (note that both G's have smaller diameter bakelike bases)
RCA 6H6GT with intermediate T9 envelope
Tung-Sol 6H6GT/G with squatty T9 envelope
General Electric 6H6 metal envelope

This photo shows four 6H6 metal type ones as follows:

RCA Radiotron early "flat top version with getter bump
RCA Victor with the common dome top
Westinghouse Radiotron with unusual bright metal base collar
Heintz and Kaufman "Gammatron" brand with red painted envelope
The photo above shows "ST" versions of the 6H6G with different
internal constructions as follows:

Hytron with aqua-dag inside the envelope.
  (this is the only one I have ever seen with aqua-dag)
Zenith with the diodes within the "T" portion of the envelope
Zenith with diodes located right at the shoulder of the envelope
CeCo with diodes below the shoulder and with supports to the "T"
  portion of the envelope
Zenith with "GT" style diodes and mica wafers located unsupported
  below the shoulder