I must have missed it!
1935 to 1945 or even 1946 a four digit model number is used. 5001 in 1935 is first. Most but not all are also Lissen Radios (up to 1941 when London Factories destroyed).
The highest known Model in 5nnn series is 5318 believed to be Bakelite Table Model version of Model A. It would be Octal version of Ever Ready 5218 Bakelite (1939)
which used Edge connect tubes.
In 1942 the Ever Ready Radio production moved into Block "A" at Park Lane Wolverhampton.Quick 1.4V Tube history of UK
Letters used on Serial Number plates, Some are Model Names.
- 1938 Sylvania released the Octal 50mA 1.4V valves 1A7G 1N5G 1H5G 1A5G 1C5G & 3Q5. Previous best was 100mA 2V for Lead Acid. The Audio output was 3 versions 50mA Low power audio, 100mA or 50mA + 50mA for series (2.8V) operation. 1A5G 1C5G & 3Q5
- Philips/Mullard and others released these designs as Edge Connect in early 1939 DK1, DF1, DAC1 and DL2
- Late 1939 RCA shrunk them to B7G, first Radios produced in 1940 1R5, 1T4, 1S5, 1S4 or 3S4
During WWII in UK the B7G tubes only used in Covert/Resistance sets.
- 1940 Osram / Marconi etc in UK produce Octal copies of the RCA/Sylvania Octal X14 Z14 HD14 N14 N15 & N16 ) Mazda releases a Mazda Octal version of the range!
- 1942 to 1945 Sets using Edge Connect and Mazda Octal ship with mix of valves and eventually all US Octal.
- 1945 Mullard and other European numbered versions of 1A7G 1N5G 1H5G 3Q5 as DK32 DF33 DAC32 DL33
- 1945 - 1947 Battery sets using Octal 1.4V can be any mix of US or European numbered valves
- 1945 - 1950 Presumably due to shortages some makers shipping 120V + 2V Lead Acid 100mA 2V valves with up to four different bases, Edge, 7 pin, International Octal and Mazda Octal for Battery sets!
- By 1946 there are no stocks of Edge Connect valves. Production may have almost ceased 1942 / 1943. Mullard issue conversion guide for existing sets.
- 1946 Any UK sets using B7G use RCA or other imported tubes: 1R5, 1T4, 1S5, 1S4 or 3S4
1947 European sourced (Philips, Mullard others) copies DK91, DF91, DAF91, DL91 and DL92 (1R5, 1T4, 1S5, 1S4 and 3S4)
- 1949 Sylviania did the 1L6 B7G for Transoceanic as 1R5 couldn't be used. (later 1U5 or DK92 work as replacements for this rare valve, but need wiring changes).
- 1950 the DL93 and DL94 give nearly x2 audio power on same filament as DL92, The DL94 moves g1 away from beside anode pin and deletes 2nd anode pin so not pin compatible with DL92
- 1951 the DK92 has different grid layout and extra grid pin. Really an Octode type of Heptode. (DK91 is Hexode type Heptode). Thus not pin compatible with DK91 as an extra +B screen grid pin used (pin5). On 1R5/DK91, pin 1 & 5 are connected internally and go to 0V. Less L.O. Leakage out on RF in and higher SW frequencies.
- 1952 Philips develop VHF capable DC90, 50mA. VHF Portables in early 1953
- 1952 Philips develop DM70 VFD type Magic Eye instead of CRT based like EM34. Only 25mA! DM71 is cropped version for B8D socket.
- 1953 Philips deliver DK96, DF96, DAF96 and DL96. The DK96 is DK92 pin compatible (though not quite as good at SW) and DL96 is only DL92 audio power, half DL94 power but DL94 pin connections.
- December 1954 Philips demo VHF DF97. Sets using it for VHF in 1955. It brings out the g3 to separate pin. A DF96 will work in DF97 IF socket, but not vice versa. Used wired as Triode instead of DC90 for VHF Oscillator/Mixer in same circuit, but 25mA instead of 50mA. Most German AM/FM MW/LW/VHF sets use DF97 only for VHF mixer/osc and use DF96 for 10.7MHz/460kHz (or nearby) IF. Vidor Vanguard uses entirely DF97s, AM uses a pair of DF97 in "Hexode/Triode" type of circuit Mixer/Osc configuration, the "triode" doubling as VHF Miser/Osc and "Hexode" as FM IF 1st pentode amp
A 1945/1946. Based on 1939 5124 / Lissen 8514 series Trader sheet 450. Many models. Early 521x are Edge, later USA Octal and A is USA or Mullard Octal numbers.
B 1947 Logically should have been 1946, delayed due to shortages? B2 adds Long wave in 1947 or 1948
C, C/A, C/E 1946 Octal, 1947, 1948 B7G (suggesting shortage of B7G, European copies of 1940 RCA)
D Listed by GEC as using a AD3, but what is it?
G/A, G/B Listed by GEC as using a AD3, but what is it?
J 1949 SW only Saucepan. May have been up to 4 versions. Last two in 1954 (SW only and SW + MW)
K 1949 - 1953 same chassis on Sky Queen
N 1951 Briefcase. N3 is revised tuning mechanism, power switch and Dx96 valves
P 1954 Sky Prince
Q 1953 Sky Queen
T 1950 for Table version of K, three versions, incompatible socket wiring
V 1955 Sky Monarch AM/FM
SC 1955 Sky Casket
SE 1957 Sky Emperor
SK 1956 Sky King
SM 1958 BEREC Matador (= Ever Ready Sky Baronet)
SLR 1958 Sky Leader
SMR 1962 Sky Master
SPE 1961 Sky Prince Transistor
It will be interesting to see what other abbreviations used.