Braun S44M

1955

Condition and performance:

	Cabinet:	70%
	Reception AM:	80%
	Sound Quality AM:	80%
	Sound Quality P.U.:	80%

Features:

	P.U. Entrance:	Yes
	Tape Recorder Entrance:	No
	Extra Loudspeaker Output:	Yes, 5 Ohms
	Loudness:	Yes, only on bass
	Treble Control:	Yes
	Bass Control:	No
	Tone Register Switches:	No
	AM Bandwidth Switch or Control:	No
	Tuning Indicator:	Yes, EM80
	Build-in Antenna:	No
	Build in Ferrite or Window Antenna:	No

Technical Specifications (Partially measured):

	Tubes:	ECH81, EF89, EAF41, EL41, EM80.
	Wave Bands:	LW, MW, SW from 13 - 50 meters
	Intermediate Frequencies (IF):	468 kHz
	Loudspeaker:	Oval type, 15 x 22 cm
	Resonance Frequency Fs:	125 Hz
	Frequency Range Power Amplifier:	25 - 20,000 Hz (after modification)
	RMS Output Power at 5 Ohms:	2 Watts
	Cabinet:	Wood, brown lacquered.
	Dimensions:	50 x 31 x 22 cm
	Mains Power Voltages:	110, 127, 150, 220, 240 Volt~
	Mains Power Consumption	?
	Retail Price	?

Description:

Braun is still a famous brand, mostly of their electrical tooth brushes and shavers, however, in the past Braun made very well radio's, turn tables, Hi-Fi sets and Hi-fi loudspeakers. This radio is a standard AM radio of very good quality.

Repairs:

Coupling capacitor of 10 nF between the EAF42 and EL41 is replaced.
Reason: The grid resistor of the EL41 has 1.5 Volts. It should be 0 Volts, otherwise the EL41 withdraw too much current, which can destroy the EL41, output transformer and the power power supply.
100 kHz oscillation of the power amplifier. The cause is the negative feedback circuit. Amplification gain is also too low.
Solution: Feedback resistor of 300K en feedback capacitor of 3 nF is removed.
1 nF capacitor on the output transformer is left away.
Reason:Together with the negative feedback circuit, the power amplifier was unstable before.
Loudness capacitor of 5 nF is replaced by 4700 pF 1000 Volt.
Reason: No bass sound before. Now the sound is more full.
10 nF and 25 nF capacitors on the volume potentiometer are replaced by 10 nF 630V and 22 nF 630V
Reason: Turning on the potentiometer gives a crackling sound. Now the crackling sound has disappeared.

The high voltage supply is 270 Volts, which is more than sufficient.
The radio is sold in 2003

Performance:

Despite the low amplifier output power of 2 Watt RMS, the sound quality is good and even loud without distortion. Main cause of the low output power is the cathode resistor of 270 Ohms on the EL41, but this ensures a very long life time of the EL41.
The power amplifier is now without voltage feedback, but there is current feedback, because the cathode of the EL41 isn't decoupled by a capacitor.

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