[Dept. of Computer Science]

Philips BX998A

This radio is not mine, I just looked into it for my collegue.

Our Department and University.
See my own radios too!

The BX998A was Philips' top model of the nineteen fifties. The price of this radio was near 1200 guilders, about the same as the price of a small car; of course, the radio lasts longer and gives more fun! There was also a console model FX995A with built-in pickup, and this machine would sell for about 2800 guilders.

The radio is equipped with sixteen tubes and offers the best sound quality of the time, as well as some funny and some useless gizmos. Actually, a few tubes could have been saved easily, but potential buyers would rather be attracted by having this many tubes than by a fifty guilder price reduction. The FM tuner uses two tubes (EF80 and EC92), while single tube units (with ECC85) were available at the time. Also, the third IF tube (EF85) could have been saved by using the ECH81 tube as the first IF stage for FM reception, a technique that was well-established as early as in 1953.

The radio is based on the bi-ampli concept, which means that bass and treble notes are amplified seperately; the ouput tube for trebles is the very common EL84, while the bass output comes from a series-balanced output stage with two PL81 tubes. Treble and bass can be regulated separately (the treble control also narrows the bandwidth of the IF strip for the AM bands), and of course there are separate speakers as well.

A very attractive feature of this radio is its motorized bandswitch; it is controlled by nine pushbuttons, but the actual bandswitch is rotated by an electric motor inside. The chosen band is indicated by having electric lights on the front panal. You can intimidate your friends by pushing a button and then hear the motor work itself through the positions of the switch and making the pilot lights light up one after another, until the motor stops at the chosen band. To avoid heavy noises during this operation, the motor voltage is directed by X1 to cut off the first audio stage.

The FM unit can work in two modes: the `quality' one features silent tuning, where the hiss between stations is suppressed and the detector is only activated when a strong station is tuned. Diode X2 in the anode circuit of the RF stage (EF80 tube) prevents overloading of the mixer EC92.

The Short Wave capabilities of the BX998A make it a real all-wave receiver; all frequencies between 517 and 26500 kiloHertz are covered. The RF stage gives good image rejection, and due to three IF transformers the selectivity is adequate. On the two highest bands (5.1 MHz and higher) fine tuning is offered with a little knob and an additional miniature dial, illuminated only when these bands are selected, of course. CB communication (27 Mc band) can be overheard, but this band is not so active anymore nowadays. One almost regrets the lack of a BFO, but probably the richest Philips clients at the time were not interested in hearing CW, and SSB telephony was not used a lot at that time. Also, Philips might not dare to include a functionality that its costumers wouldn't be able to use properly.

The set has built in antennas for FM (dipole) and MW/LW (ferrite rod rotatable from the front). There is a `local MW' dial on which one station can be preset; this dial is illuminated when local MW is chosen.

The radio shows its age in its design, because it is, though high-end, definitely a child of the fifties. The entire radio is monoral; stereo reproduction (of records and tape) was introduced to home entertainment only in the late fifties, and stereo FM transmissions came later still. A more regrettable sign of the era is the simplicity of the tonality control: there are `just' two controls for treble and bass, while many later sets have four or five band equalizers and presets for speach, jazz, orchestra, etc. My explanation reads that in 1955 there was just one acceptable style of music, namely classical music, while pop music didn't exist and jazz was hardly played by the class of people buying this radio.

The top model of the sixties was, understandibly, different; here is apicture of the Philips F9X38A:

Technical data for the BX998A:

Type:
Philips BX998A, The Netherlands 1955.
Bands:
LW (870-2000m), MW (185-580m), SW1 (57.5-185m),
SW2 (20-59m), SW3 (11.3-20.4m), FM (3-3.43m).
Int. freq.: 452 kHz and 10.7 MHz.
Cabinet:
Wood, weight 27kg.
Tubes:
This is a sixteen tube radio.
EBF80 (RF stage AM), ECH81 (mixer AM), EF80 (RF stage FM), EC92 (mixer FM), EF89 (1st IF), EBF80 (2nd IF, det AM), EF85 (3rd IF, FM), EAA91 (det FM), ECC83 (preamp AF and trebles driver), EBC41 (bass driver), 2xPL81 (bass output), EL84 (trebles output), 2xEZ80 (rectifier), EM34 (magic eye), OA50 (suppressor), OA72 (signal limiter FM), 15 dial and pilot lights.
Controls:
Volume, tuning, bass, treble & bandwidth,
antenna rotate, fine tune (SW2/SW3), tune local MW, Pushbuttons for LW, MW, local MW, SW1, SW2, SW3, phono, FM quality, FM sensitive, power.
Here is a chassis picture:
Gerard Tel, gerard@cs.uu.nl.