Receiver 1920
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Four valve battery radio for reception of medium and long wave
The M4 is a four valve receiver with variometer tuning. This is a luxurious model with a mahogany cabinet. The dark blue aluminium front is divided into three sections: the left section contains the knob for primary tuning, in the middle a small scale, a wave length switch and secondary tuning (with fine tuning). The left section contains reaction control, a loudspeaker connection and a lever for selectivity control (stronger/weaker). The wave length switch has three bands: 200-600 meters, 600-1300 meters and 1300-3000 meters.
George William White in 1923
The radio, designed by British engineer George William White, was presented at the I.R.T.A radio fair in Amsterdam, on October 2nd, 1926. NSF aimed at a receiver that had to be easy to operate; a complicated radio like the V4, with 13 knobs, was not a commercial success.
In the user manual emphasis was put on the fact that the radio could easily be tuned. The big knob had to be turned to the frequency used by the transmitting station, then only the knob in the second section had to be used to tune the antenna. It is very funny to read that one did not have to wait any longer until an even better receiver came on the market. The M4 was considered to be the end of radio design; only minor improvements could be expected in later models...! It was a popular receiver, of which about 2000 were made.
The receiver was available in three models: the M4 without doors (fl 250,-), the M4A with doors (fl 265,-) and the M4 Luxe, a luxurious model with doors (fl 285,-).
1926 Was a busy year for NSF. A whole range of new receivers came on the market: the VARA receiver, made for Dutch broadcasting organization VARA, the M3, the M4, the V4 and for Erres the Detectofoon-series I to V and the Corrector separating filter.
The actual tube set is based on an NSF-service book issued by Philips in 1932. The A435 was not available in 1926. The original tube set was: A410, A409, B406 and B403.
Serial number: 1616
Dimensions (whd): 54 34 32.5 cm
Made in: 1926
Purchased in: 2011
Voltages: 4V/60V/120V/-4.5V
Weight: 11.9 kg
Click on a valve for more information

Circuit  Article (in Dutch)

What was broadcast in 1925?


Listen to "Blue Evening Blues" by the Belgian-Dutch formation "The Excellos Five", Louis de Vries (tp), Henri van den Bossche (tb), Alphonse van Asbroek (cl, s), Joop de Leur (p), Bob Kierberg (dr, ld), recorded Berlin, December 1925

Mahogany cabinet with doors closed
showing the Marconi variometer (left) primary tuning (middle), reaction control (right) and the four valves. Two rheostats can be seen on the left of the ebonite strip. The left one is used for the HF tube and the detector tube; the other for both LF tubes.
The chassis of the receiver, seen from the back
Two Marconiphone transformers (ratio 1:3) can be seen below. The tuning condenser in the middle is by Sterling. The ebonite strip in the middle holds the four tube sockets.
Type plate
Details: primary tuning Wave length switch Reaction control
Advertisement for the M4 in newspaper NRC, October 1st, 1926. The advertisement shows the M4 without doors. The picture below shows the same model from the collection of Kees Koren
Leaflet for the M4
Technician A. van Burk in the KRO control room. Next to him an NSF M4.
1926. The NSF Radio stand at the IRTA in Amsterdam.
1927: NSF M4 radio that brings music to the workers of sugar factory Cliever in Rotterdam. Managing director L.J. Gillet has purchased a complete radio set for his home. Several connections were made to the factory so the workers could hear music, which had a good influence on their daily productivity.

This page was last edited on 01.11.2021