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.
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
Interior
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.
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