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AERODYNE  MERLIN, RAVEN   MAKES OF SET  BLACKBIRD  SWALLOW  CURLEW  MERLIN  EPITAPH 

 

MERLIN

This is the set that is also shown on the cover of the leaflet. Another TRF design, battery operated.

"The 'Merlin' is in every way a deluxe battery receiver; its outstanding distinctive appearance is on a par with its brilliant performance. A glance at the specification will show that it has everything that is necessary in an up to date and high class receiver, and a demonstration will prove how efficient and delightful a really modern battery set can be.

This receiver is acknowledged the leading battery set of the season."

 


Terminology explained

Gramophone pick-up sockets = the acoustic gramophone was very popular before radio held centre stage, and continued for many years. It was possible to purchase pick-up arms to adapt the acoustic systems. These either replaced the old tubular tone arm or fitted in place of the acoustic head. Electric amplification was needed for these magnetic devices and the domestic radio had a ready-made amplifier in the form of its AF and output stages. Many manufacturers fitted suitable 'gram' sockets, though on the AC/DC mains sets they were not always very successful, or safe!

Illuminated wavelength scale = many battery sets were fitted with these, despite the obvious drawback of power wastage.

RAVEN

This set came with a cabinet in a choice of two finishes, OAK or EBONISED (black). Bakelite adornments on the Oak, Chromium on the ebonised. They even boasted that the metal chassis was finished in grey cellulose.

Whichever way you look at it, this was a remarkably low-cost set for the time. A straight (TRF) three-valve unit with no frills except a clock! Note the use of a balanced-armature loudspeaker. These were more sensitive and cheaper to manufacture than PM moving coil types, and other makers used them on low-cost sets, but the frequency response was poor, especially in the lower register, perhaps the reason for the use of a particularly large cone. 

The claim that the set is an example of 'progressiveness' is founded on rather shaky ground, as the technical design was very conventional and in fact outdated in some ways. And what about that loudspeaker! Hardly progressive.

 

"The 'Raven' is yet another example of Aerodyne progressiveness. It is the only battery set which incorporates a timepiece at this price. Under normal conditions not only will the set receive the majority of British stations, but Foreigners as well, with quality, purity of tone and volume unsurpassed by any other receiver in its class. As regards the cabinet, you can have your choice of a beautiful ebonised cabinet with Chromium fittings or a figured Oak with Brown Bakelite fittings."

 


Terminology explained

TRF = tuned radio frequency. An amplifying stage (valve) is tuned to receive signals by means of an inductance/capacitance circuit. The capacitor is adjustable to enable selection of stations across a BAND of frequencies (i.e. long wave BAND, medium wave BAND). The amplified radio signal is then DETECTED by a diode and the resulting LF signal is further amplified and fed to the loudspeaker. This is the basis of the TRF receiver, though often more than one stage of tuning is involved. This method was the earliest form of radio reception method and was superseded by the more efficient SUPERHETERODYNE system.

Balanced Armature Loudspeaker = the armature is a winding on an iron rod pivoted centrally between the poles of a magnet. signals fed to the winding cause it to be attracted to one pole whilst being repelled from the other, and vice-versa. This makes for a very sensitive device, needing only low-efficiency magnets. The same system is used for some pick-up cartridges and headphones. The cone of the loudspeaker is linked to one end of the iron rod and therefore vibrates in sympathy with the movement, creating sound. In order to get the best from the system, the cones were invariably of a large size, typically 12" (30cm).

 

 

 

VINTAGE RADIO world: SIXTEEN YEARS OF WEB PRESENCE