Phantom XV (15)

Halford Radio Ltd.; London

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  • Year
  • 1938
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 347494

Click on the schematic thumbnail to request the schematic as a free document.

 Technical Specifications

  • Number of Tubes
  • 13
  • Main principle
  • Superhet with RF-stage; ZF/IF 110/465 kHz; 3 AF stage(s)
  • Tuned circuits
  • 9 AM circuit(s)
  • Wave bands
  • Broadcast, Long Wave and 2 x Short Wave.
  • Power type and voltage
  • Alternating Current supply (AC) / 230 Volt
  • Loudspeaker
  • Electro Magnetic Dynamic LS (moving-coil with field excitation coil) / Ø 14 inch = 35.6 cm
  • Power out
  • 20 W (undistorted)
  • Material
  • Wooden case
  • from Radiomuseum.org
  • Model: Phantom XV - Halford Radio Ltd.; London
  • Notes

  • Phantom XV (15)

    Separate circuits for long-distance & local quality reception

    One of the principal activities of this firm is the design of special cabinet work to ensure that the wireless receiving installation will blend satisfactorily with period & other expensive furnishing schemes. There is a wide range of more or less standard designs at prices ranging from 17 to 150 guineas, but when none of these exactly fulfills individual requirements, alternative designs are submitted & the cabinet is made up specially. 

    It goes without saying that the foundation of this work must be a receiver chassis of the highest possible standard, & in their latest design, the makers have shown a refreshing individuality of thought which distinguishes it from the ordinary run of mass-produced multi-valve sets.

    Not only are separate superheterodyne & straight circuits available for distant reception & high-quality reproduction from the more powerful stations, but separate IF amplifiers are used for shortwave & normal broadcast reception, the former working at 465 kc, & the latter at 110 kc/s. The change-over from straight to superhet is made by an independent switch & the IF frequency is selected automatically by the wave range switch.

    In the interest of quality on medium waves, a hand-pass input filter precedes the first pentode RF amplifier. When using the straight circuit, a second RF stage is switched in & the output from this is taken to the triode section of the second detector stage, which is modified to operate as a power grid detector. With the superheterodyne circuit in action, the output from the heptode frequency changer passes through one of 2 pairs of IF valves to the double-diode signal & AVC rectifiers. The upper pair of valves in the circuit diagram are coupled by iron-cored transformers tuned to 465kc/s & are in the circuit on the shortwave ranges. The lower pair is tuned to 110 kc /s & has air-cored transformers.

    In the latest production models, two degrees of selectivity are provided by a third-tuned circuit. The alternative bandwidths are 6 kc/s & 9 kc/s, & the switching is combined with the tone control.

    Thus, the first two positions of the switch give maximum & medium-high note response with 9 kc/s bandwidth & the remaining three studs, maximum, medium & minimum response with 6 kc /s bandwidth in the IF amplifier.

    Alternative Volume Controls

    Both audio & radio-frequency volume controls are provided, the latter controlling the RF stages in the straight circuit & both the RF and IF stages of the superhet circuit, for medium & long waves. To avoid all possibility of detector overload distortion in the straight circuit, no audio-frequency volume control is fitted and volume is regulated by the RF input. 

    A pentode valve connected as a triode acts as the second AF amplifier in the superhet, & the first AF amplifier in the straight circuit. It is followed by a parallel-fed transformer, the split secondary being connected to two double-triode output valves in push-pull.

    The HT voltage is 400 & under the conditions of operation, the power-handling capacity of the output stage is 20 watts. Current for the 2,500-ohm loud-speaker field is fed through resistance from the main HT line. A single full-wave power rectifier supplies the whole equipment & smoothing is done by a two-stage filter making use of a total smoothing capacity of 45 mfd.

    Wireless World Nov 17, 1938, Page 440

  • Author
  • Model page created by Gary Cowans. See "Data change" for further contributors.

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