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Front page of brochure.
The author came across a document for this amplifier in a pile of papers. The document was in fact a single printed broadsheet as the instructions for an amplifier kit. It appears that this was the design of the mono amplifier that was purchased some years ago. Further research discovered a PDF of a complete brochure.
Audio Amplifier and power supply.
The full broadsheet has four columns and folds to leave the right side showing as title and verso.
The instructions with the kit.
The brochure version is divided into pages and can be found here.
The amplifier when purchased needed some work and this was never done. During the experiments on Simplex Stereo the output transformer was 'borrowed' and together with a SE EL84 output transformer gave the best results in the simplex amplifier.
Top of Chassis.
The chassis is finished in a grey hammer finish paint. The valves are identified by Dymo type labels.
Underside of chassis.
Construction features tag-boards. Tag-board construction was the accepted way of mounting components at the time and this has the feel of 1960's assembly.
Component View.
The amplifier came with a fitted aluminium bottom plate attached to the side flanges of the main chassis. The centre bracing looks overkill. The soldering around the main HT capacitor shows the use of a large soldering iron but still not quite large enough to get a good solder flow.
Soldering.
A professional wireman of the time would attach components mechanically as well as electrically. For a valve-holder for instance, a component lead would be threaded through the hole in the pin connection and then wrapped around the tag and finally twisted around the incoming lead. The solder would then be flowed around the whole joint.
It can be seen in the above photograph that the builder has inserted the lead through the hole in the tag and then used solder to hold the component. This is typical of home construction. Additionally professionally constructed equipment of the time had neat arrangements of components as can be seen here.
Thanks to World Radio History for the PDF. website.
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