Scott-Taggart ST300

 John Scott-Taggart was a radio expert that designed sets for the home constructor. It was said that his designs gave the very best performance for the parts used in them. Certainly he included lots of controls so that peak performance could be achieved by twiddling the various knobs. Later sets were designated ST400, 500, 600 etc.

 I'm not sure at this stage whether the case was bought ready-made, or perhaps as a set of parts or whether it was constructed by the builder of the set, who, if he did design and make the case must have obviously been a dab hand at woodwork.The finish of the plywood surface is utilitarian and he didn't bother to french polish it. The paint finish is now peeling off and the grain of the wood is very pronounced. The radio front panel is made from plywood, rather than ebonite, which may have been going out of fashion when this set was made. The terminal panels which are made from an early form of ebonite and are almost certainly the oldest parts of the set and maybe one of these (the second from the right) dates from WW1.

 There are three valves in this model. On the left a Mullard PM2A B4 triode, above it another B4 triode, a Mullard PM2DX and to the right a Cossor B4-based 215SG tetrode. All have 2 volt filaments and all are marked "BVA". You can maybe also identify the following parts... a Telsen interstage transformer, a couple of HF chokes, the brown dog-bone shape made by Telsen (known as a "Binocular" choke) and the circular black one made by Lewcos, and a couple of fixed condensers, a 1uF which tested as 1.25uF with an ESR of 0.04 ohms which is remarkably good and a brown bakelite Telsen mica condenser whose value is not visible. On the front panel is mounted... A pair of Ormond tuning condensers (one brass and the other aluminium), a JB aerial tuning condenser, a pair of solid dielectric variable condensers.. one 0.0001uF made by Telsen and the other an anonymous 0.00015uF which is foreign made. The tuning coils were made by Colvern.

 The grid-bias battery was usually clamped onto the baseboard and is now missing, together with its leads. The front end of the set below uses a screen grid valve and, to help with stability, a copper sheet has been tacked onto the plywood baseboard. The vertical panel is steel rather than brass so is now going rather rusty.

 The back end of the set has an RF stage with reaction so that with its pair of RF stages, the user would have to keep the pair of tuning condensers in track. The coils used are commercial types so would have been reasonably well matched, resulting in the dial readings being about the same for any given station. Two sets of coil windings are provided, giving reception on medium and long waves. With all these types of sets, usually constructed between about 1928 and 1932, a record needed to be kept showing dial settings for ones favourite stations.

 This example of the ST300 includes an integral loudspeaker (incidentally the designation "ST300" is said to relate to the number of valves.. times 100 of course!) Many people stretched their funds to the utmost to buy the basic kit and made do with their crystal-set headphones. The constructor of this one clearly planned his to include an early moving coil permanent magnet loudspeaker. Once I'd cleaned the label I could see it read Celestion Model 9 PPM.


 Not many resistors....two are shown below. Different voltages, rather than being defined by resistors as would be the case nowadays, are provided by the HT battery which would usually supply two or three voltages for the valves.
 A rather odd condenser, being from 1946 and thus implying the old receiver was working maybe even in the 1950s or later. Alas the newer electrolytic marked 2uF 275 vw measued only 1uF with an ESR of greater than 20 ohms which makes it pretty poor.

 Summarising my findings; this set should be easily restorable because it's complete and shows signs of being rejuvenated either in the late 1940s or 1950s. Below is a rather glowing advertisement from 1931 for the RF valve used in the ST300.


 I found this Practical Wireless article on making a Scott Taggart ST300 which I've scanned and reproduced here..

click the picture of the radio to see it

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