The Zenith Trans-Oceanic
Tube Model Lineup 1951-62

Because my interest is in the tube Trans-Oceanics, and specifically the H500 and 600 series, I present an outline of the variations of these two models.

Introduced in May 1951, the H500 "Super Trans-Oceanic" was a complete redesign from the earlier G500.

The 'baseline' model used a 1S5 tube for the detector/AVC and featured a two-pin headphone output on the rear of the chassis.

Revision 'A', introduced around July 1951, changed the detector/AVC tube to a 1U5, but retained the headphone output arrangement.

Revision 'B', introduced around November 1951, saw a conventional 1/4" jack-plug socket for the headphone output.

Revision 'C', introduced around April 1952, featured a 'low-voltage' switch on the rear of the chassis for use when the line voltage dipped below 110V.

Revision 'D', introduced in mid-1953, is easily spotted as it featured a cut-out for a sixth tube - a 50A1 current regulator. This final revision is reckoned to be the rarest and it has been suggested that it was released commercially to use a surplus of the R-520 militarized chassis.

600 Series

L600 - Introduced in 1954, the first of the 600 series was denominated the L600. It used chassis number 6L41 and is easily spotted by its rear headphone jack and smooth carrying handle. The handle became 'ribbed' from around May 1954 onwards but neither style features the 'pivot hole' for the Wavemagnet antenna.

R600 - The next variant, bearing chassis number 6R40, was introduced in 1955 and sees a conventional 1/4" headphone jack on the front panel, as well as a hole in the handle to allow the Wavemagnet antenna to be rotated and thus provide a primitive RDF capability.

T600 - The 1956 variant of this radio features an RCA phono socket on the rear of the chassis and a slide-switch to select radio/phono alongside it. Earlier chassis numbers are 6T40, later ones 6T40R and 6T40Z.

Y600 - The Y600, introduced in 1957, appears identical to the previous version but uses the 6T40Z chassis - the case lid will be stamped 'Model Y600'.

A600 - Reaching maturation, the A600, introduced in 1958, sees Band II extended to 9MHz. It uses chassis number 6A40.

B600 - Last of the tubed Trans-Oceanics, the B600 was produced from 1959 to 1962. It also used chassis 6A40 but can be distinguished by a "CSL" sticker near the antenna connections and, strangely, often features a white baseboard.


Last update: 21st March 2012 Comments & Suggestions to