Bang & Olufsen Beomaster 900K

1965

Condition and performance:

	Cabinet:	90%
	Reception AM:	100%
	Reception FM:	100%
	Sound Quality AM:	80%
	Sound Quality FM:	70%
	Sound Quality P.U.:	70%

Features:

	P.U. Entrance:	Yes
	Tape Recorder Entrance:	Yes
	Extra Loudspeaker Output:	Yes, 2x 4 Ohms
	Loudness:	Yes, only on Bass
	Treble Control:	Yes
	Bass Control:	Yes
	Tone Register Switches:	No
	AM Bandwidth Switch or Control:	No
	Tuning Indicator:	Yes, analogue meter
	Build-in Antenna:	Yes, FM and SW
	Build in Ferrite or Window Antenna:	Yes, LW and MW
	Separate AM/FM tuning:	Yes

Technical Specifications (Partially measured):

	Transistors:	All Germanium types.
	Wave Bands:	LW, MW, SW, FM from 87.5 - 108 MHz
	Intermediate Frequencies (IF):	452 kHz, 10.7 MHz
	Loudspeakers:	?
	Resonance Frequency Fs:	?
	Frequency Range Power Amplifier:	?
	RMS Output Power at 4 Ohms:	2x 6 Watts
	Cabinet:	Wood, brown lacquered.
	Dimensions:	74.5 x 15 x 21 cm
	Mains Power Voltages:	220, 240 Volts~
	Mains Power Consumption	15 - 65 Watts
	Retail Price	?

Description:

Bang and Olufsen are famous by their design. Less famous is the technical innovation of their electronics, but the technical innovation is often better, compared with other major brands. The Beomaster 900K is original and the performance is still well, so this is a very reliable radio set which can play for many decades without any repairs needed.

The Beomaster 900K is a compact stereo radio of 1965. It is also fully transistorized, which results in less power consumption and less heat. After switching on,, the radio operates after a few seconds.

The chassis can be easily removed.

The balance control is placed at the back side as a preset potentiometer.

The bottom side shows very good capacitors of Philips.

The top side shows good printed circuit boards and a very long ferrite antenna.

Repairs:

After a few years of playing, the reception became dead.
The AF116 transistor makes a shortcut and is replaced by an AF126. Since then the radio works perfectly again.

Performance:

The Beomaster 900K is very sensitive in radio stations reception.
The audio quality is less than expected and misses quite a lot in the top high frequencies.

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Download the schematic diagram.