VRW  PUBLICATIONS          HOME   |   BOOKS  |   SERVICE DATA   |   RESTORATION   |   RADIO HISTORY

 

AERODYNE BLACKBIRD   MAKES OF SET  BLACKBIRD  SWALLOW  CURLEW  MERLIN  EPITAPH

 

 This is the cover of the leaflet (right).

 Nearly all the aerodyne models of the time were named after birds. The 'Merlin', pictured here, is typical of the design styling. Very Art-Deco in Walnut veneered ply with contrasting cross-bandings and boasting a chrome-finish clock, this was a three valve battery TRF set with medium and long wavebands on the illuminated dial. Typically,  the basic cabinet is a simple rectangular design, using stepped 'Deco' shaping to the feet and the inlays to help prevent visual monotony.

For more about this set, click the 'Merlin' button

The 'Blackbird'

"MAINS PERFORMANCE FROM THIS MODEL. This is a 4-valve class 'B' battery receiver. Class 'B' is a new development in battery sets, giving 'MAINS' results from an ordinary HT battery.

It is a circuit arrangement that enables a battery set built on the principle to handle enormous output without a trace of distortion with normal HT consumption.

This receiver is up-to-date in everything. Band-pass input, variable Mu HF stage, power grid detector, Class 'B' output, permanent magnet moving coil speaker, housed in a beautiful Walnut cabinet with Rosewood inlay. This latest Aerodyne achievement gives an output of 1,300 milliwatts with an economical HT consumption."

 

 


Terminology explained

BVA = British Valve Association. A trade cartel primarily designed to ring the prices of valves and keep them artificially high by removing competition within the trade.

Power Grid Detector = this is leaky-grid detection but using rather smaller values of both grid resistor and grid capacitor than the 'conventional' method. It uses a much higher anode voltage and for that reason is mostly found in AC mains (indirectly heated) valve circuits. The advantage is a virtually distortion-free detection process.

Class 'B' = a form of push-pull AF output stage in which a special double valve is used instead of two separate valves. A driver (phase splitter) valve is still needed, of course. Used in battery designs to produce large values of low distortion output.

 

 

 

 

 

VINTAGE RADIO world: SIXTEEN YEARS OF WEB PRESENCE