Before the war KB produced (as far as I can establish from the service data) a large range of very high quality receivers. After the war they produced a number of slightly unusually styled sets, but still with the emphasis on quality. Many of there sets, such as the "Toaster" and the "Minuet", were AC only (with mains transformers), at a time when other manufacturers were cost-cutting by using AC/DC designs (with dropper resistors).

Nick kindly sent me the following information about the ITT/KB company structure:

Kolster Brandes seems to have originated in Canada but was owned by the ATT/ITT conglomerate from the late 1920s. STC in the UK controlled KB directly from the late 1930s and STC itself was a UK subsidiary of ITT, starting life as the UK branch of Western Electric, which was the manufacturing arm of ATT. All very complicated, and the connection was only publicised later when products were first sold as ITT/KB before KB was dropped altogether and products were sold purely under the ITT name.

BM20

Wavebands - MW, LW Valves - 6A8GT, 6B8GT, 6V6GT, 6X5GT Date - 1947 Status - Information only

The BM20 is quite an interesting set, both in terms of the cabinet and the circuitry. The cabinet is made from two similar mouldings, which gives a pleasing appearance from the front or the rear.

The circuit is a three valve (plus rectifier) superhet, in which one valve performs the three functions of IF amplifier, detector and reflex AF amplifier. The screen grid of the pentode section acts as the AF amplifier anode. It is difficult to follow the circuit operation from the circuit diagram, and the Trader service sheet does not really explain it, but it gives good results.

Note that because of the small cabinet and rather packed layout, valves having GT envelopes were specified. The larger G envelope versions of these valves will not fit.

The left photo (showing a normal white cabinet in a poor state) was taken from the Vintage Radio Database website
The right photo (showing a rare speckled cabinet) was scanned from the book Bakelite Radios

BM30

Wavebands - MW, LW Valves - 6A8GT, 6B8GT, 6V6GT, 6X5GT Date - 1947 Status - Repaired for a customer

The BM30 is electrically identical to the BM20 (above), but is housed in a more conventional wooden cabinet.

This photo was kindly supplied by Chris Stedham.

ER30

Wavebands - SW, MW, LW Valves - 6K8GT, 7R7, 6SL7GT, 6V6GT, 6X5GT, 6U5G Date - 1949 Status - Contributed descriptions

Mark Else provided the following description:

Also covers the FG20 autoradiogram and the radio unit of the FT50 television receiver. This receiver is unusual in that it employs two triodes in the AF stage in addition to the output valve - which is a tetrode. The second triode lives in the tone control section. The diodes for AF detection and AGC are contained with a Vari-mu RF pentode.

Nick remembers this set:

I was particularly interested in your KB page as we had KB radio and TV years ago. An uncle had your shown ER30 and I can confirm it had a good audio stage. When we used to stay with them I spent hours playing 78 records on an HMV add on connected to the PU sockets.

Thanks to Past Times Radio for the photo.

FB10 "Toaster"

Wavebands - MW, LW Valves (Original Version) - 6BE6, 6BA6, 6AT6, 6V6GT, 6X5GT Valves (Later Version) - 6BE6, 6BJ6, 6AT6, 6BW6, 6V4 Date - 1950 Status - Repaired for a customer

The construction of this set is unusual, in that it is dismantled from the base rather than the back. The advantage is that the set looks presentable from any direction, whereas most sets are not very pretty from behind!

The volume and tuning controls are positioned at the lower front corners, and look more like feet in this photo. The wavechange switch is in the lower centre.

This set is extremely popular with collectors although, like many popular sets, I really cannot see the attraction.

According to the service data there was a later version with a different valve lineup. I assume this was to take advantage of the more recent, smaller, devices that were becoming available (the output and rectifier in the original version were octal based valves). The release date of this version is not quoted.

FB10FM "Toaster"

Wavebands - VHF Valves - 12AT7, 6BJ6, EABC80, EL84 or 6AM6, EZ80 or Metal Rectifier Date - 1955 Status - Included for information

This is the VHF brother to the MW/LW "Toaster" shown above. The case is almost identical and it is shown here because of the possibility of confusion between the two models.

As well as being used as a normal radio, the set can be used as a VHF adapter for connecting to the gramophone input of higher quality sets that do not have the VHF band; the idea being that it is cheaper to buy this set and use it with a high quality existing set, than to replace the existing set with something equivalent. The switch in the bottom centre of the front panel selects either "Radio" or "Adapter" mode; in adapter mode the speaker is replaced with a dummy load and the output stage is reconfigured to give lower gain and higher quality by the addition of negative feedback.

OB10 "Minuet"

Wavebands - MW, LW Valves - 6BE6, 6BJ6, 6AT6, 6AQ5, EZ80 Date - 1957 Status - In my collection, and contributed photo and description

Richard Lamsdale kindly provided this nice photo (left) and the following information:

This is a compact set, and has a mains transformer rather than resistor. It is a plastic case, the front being removable and the insides being attached to the front plate.

It seems well designed. Inside there is a circuit board with everything attached, and the output transformer is mounted on the back of the speaker. This set works very well.

I bought one of these sets at the Autumn 2001 NVCF for (I think) £20. It is rather dirty and some of the gold printing has worn away, but otherwise it is complete.

QB20 "Minuet"

Wavebands - MW, VHF Valves - 12AT7, ECH81, 6BJ6, EABC80, EL84 Date - 1959 Status - Included for information only

The appearance of this sit is very similar to the OB10 "Minuet" above. However the QB20 is a later model and features a VHF waveband.

Like the OB10, this is an AC only set so should run fairly cool.

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