Television V180C

A television receiver for vision and accompanying sound from London or Midland Transmitters for A.C. mains (200-250 volts, 50 cycles).

Circuit

The circuit employed for the receiver is a dual-channel superhet preceded by two RF stages and is arranged as follows;

A tuned circuit couples the first RF stage to the aerial whilst band-pass transformers are used to couple the two RF stages and the triode-heptode frequency changer. All of these circuits are common to both sound and vision. The vision circuits, following the frequency changer, comprise two IF stages using bandpass coupling transformers followed by a diode detector and the video amplifier. An adjustable limiter controls the output from the video amplifier thus enabling interference to be minimised.

Sound signals from the frequency changer are amplified by a single IF stage, whilst a double diode performs detector and interference suppressor. Finally, a beam tetrode power output valve drives an 8" permanent magnet loudspeaker providing volume with high-quality reproduction.

The deflection generators are controlled by a double diode synchronising filter and in the case of "line" and "frame" scans consist of a gas-filled sawtooth generator followed by a beam tetrode amplifier. Such a system ensures minimum geometric distortion together with a high degree of stability.

The complete vision circuits have been designed to take full advantage of the present BBC transmissions, giving maximum definition and tonal range, in fact, a 10^5/₁₆in by 7^3/₄in picture of outstanding quality on a 12in tube.

The console cabinet has an emphasis on vertical lines is made by pillars that curve out from the side panels for a wider front aspect, and easier adjustment of the set position on one hand. The top, shaped at the front, is in figured medium-tone walnut, edged by darker bands running around the side and back. The controls (brown bakelite with gold rings) have a broad fluting that is pleasant to handle. Gold striped rayon speaker silk.
The cabinet is fitted with large castors. 
Cabinet design by Edin Minns.

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Elenco delle radio e altri apparecchi della Murphy Radio Ltd.; Welwyn Garden City