This is more or less an extension of the old “Valve Questions” thread,
https://www.vintage-radio.net/forum/...591#post233591.
Therein was discussed inter alia some aspects of Philips transition to the noval base from its own Rimlock form.
To recap, Philips in 1949 adopted the noval base for most of its “World Series” of TV valves, the EF80 and ECL80 being early releases in that series. There was technical justification for the 9-pin base. For example, in the case of the EF80, it enable the use of two cathode pinouts whilst retaining a separate pinout for the internal screen. In contrast, Mazda’s comparable (or in some ways better) 6F1, on the Rimlock base, required that the internal screen and the suppressor grid share a pinout in order to allow two cathode pinouts. (The preceding 6F13, also on the Rimlock base, had a single cathode pinout and separate internal screen and suppressor grid pinouts.)
With radio valves, the first big “wave” of noval releases, at least as far as Europe was concerned, arrived c.1952 with those intended specifically for FM-AM receivers, such as the ECH81 and EABC80. However, the transition had started in an apparently small way 1949. The EBF80 had a noval base out of necessity, and the unique enneode (renamed, perhaps misnamed as a nonode by Mullard) was changed from the Rimlock EQ40 to the noval EQ80 before major production began.
But there was another facet to the Philips transition to the noval base, and that related to its Australian valve manufacturing activities. There it would have appeared to have skipped the Rimlock phase (although that needs to be confirmed), instead going direct to a noval-based radio receiving base range in 1949. The initial announcement of this Australian-manufactured range, on 1949 November 29, was recorded in an item in the magazine Australian Radio and Television News 1950 January, excerpt attached:
The valves concerned were as follows:
6AN7 triode hexode, being the American designation for the ECH80, which was the ECH42 on a noval base.
6M5 output pentode, being the American designation for the EL80, which was the EL41 on a noval base.
6BD7 double-diode triode, being the American designation for the EBC81, the EBC41 on a noval base.
6N8 double-diode pentode, being the American designation for the EBF80.
(Evidently American RTMA valve designations were preferred in Australia, even though the Pro-Electron type were much more informative.)
Philips referred to these valves as being part of the “Innoval” range. I am not aware that it used that descriptor in Europe; I do not recall seeing it used in connection with for example the “World Series” TV valves.
I am not sure if the initial Innoval range were the first novals to be made in Australia. By the time of their release, AWV was already making B7G valves (6BA6, etc.) in Australia, but it might not yet have been making any novals, although it was probably importing some from RCA USA. One of AWVs’ early noval productions was the 6AE8 triode heptode in 1950; this was in fact the Osram X79, for which AWV did the American registration. In the absence of a miniature triode heptode from RCA, AWV had to look to its UK principal for what was evidently an important valve type in the Australian market.
Whether Mullard ever used the “Innoval” term is not clear, but it was absent from a Mullard advertisement for the initial four Innoval valves in Australia Radio and Television News 1950 May:
In fact, Mullard’s use of the term “9-Pin” for these valves rather than simply “noval” might be construed as a desire not to connect with “Innoval”, even indirectly.
As best I can determine, valves such as the 6AN7 and 6M5, replicates of existing Rimlock issues, were never offered in Europe. Rather the Rimlocks remained in place until their FM-AM era replacements, the ECH81 and EL84 were released.
The EBC81 (6BD7) looks as if it were held back in Europe until c.1955, about the same time as the then-new EF89 was released. Rather the Rimlock EBC41 was used until then, although somewhat displaced by the EABC80 as FM-AM receivers displaced the AM-only type. Evidence is provided by the example of the Pye FenMan II radio receiver, released in 1955 but probably the outcome of a 1954 design study, which had an EBC41 in an otherwise all-noval line-up. It also had an EABC80. Two AF triodes were anyway needed, and the use of the EBC41 both delivered the second triode and allowed the use of delayed AGC on AM. One imagines that had the EBC81 been available from UK/European production at the time, it would have been used in place of the EBC41. (The corresponding HFT111 AM-FM tuner avoided the EBC41 as not needing any AF triodes, the EABC80 triode was strapped to provide a 4th diode.)
The Philips/Mullard transition from Rimlock to noval was not a simple exercise, with different timelines in different geographies.
Cheers,