Early home built mains receiver

 This is quite a rare set because it was designed to run from the mains rather than batteries. Back in the early 1930s it was possible to convert ones TRF receiver from battery to mains by swapping the valves from 2 volt filament to 4 volt indirectly heated cathode types, but it was not only a question of its economic viability as it was the huge expense in completing the job. In the 1930s wages were low and there was a slump with large numbers unemployed and cash in short supply. Advertisers of receivers and radio components managed to maintain their businesses by offering purchase on the never-never. A new loudspeaker was offered for sale at only a few shillings (click to see) but smaller print included the actual price, and even smaller print the terms of the necessary loan which accompanied the purchase.

This receiver was probably made to run from a mains power supply from the outset. It's fair to say that most battery sets could be run from a battery eliminator driven from the mains, but these sets still needed a 2 volt accumulator for the valve filaments. With the advent of valves with "heaters" not only the HT but the heater supply could be run from the mains power pack. The set is in a sorry-looking condition.


 Below, the chassis where you can see that some parts are missing, notably two valves, the aerial coil and an interstage transformer. The remaining valve is a Mullard S4V tetrode with a B5 base and a 4-volt heater. It has the early aerial-earth logo and a BVA marking and dates from 1929.

The pair of tuning condensers carry the maker's name "Polar" and the odd-looking very early wavechange switch was made by Wearite. Under the switch is a round component which seems to be a variable resistor which uses compression to reduce resistance. It was almost certainly the reaction control. The large RF coil is a 6-pin plug-in type and is very early. This and the two RF chokes have no maker's names.


 Under the chassis looks OK. The block condenser with newspaper stuck to it is marked "1uF" and measures 1.25uF and has an extremely low value of ESR of 0.15 ohm

 The set is not an immediate candidate for restoration.

Below is a 1931 advertisement for converting a battery set to mains operation.


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