Inhaltsverzeichnis
Philips AL-990
Manufactured by Philips, Eindhoven.
Around 1982, Philips presented the AL-990 as Philips' first tabletop receiver equipped with a digital frequency display. Similar to the RF-2200 from Panasonic, the set had a rotatable ferrite antenna, that could be used for direction findung to locate a long or medium wave transmitter. For the short wave ranges a loop antenna could also be attached. Similar elaborate antenna designs can be found on several portable receivers in the late seventies.
Philips did a big technological step by integrating a frequency counter for digital frequency display and a digital clock, as a by-product.
Variants
- Suffix /00 (/40 and /51): ZF 468 kHz
- Suffix /01: ZF 455 kHz
Technical data
- frequency range: FM broadcast band (87.5 - 108 MHz), LW, MW, MB (Marine Band), 5 x SW (4.5 - 26.2 MHz).
- Frequency display: digital display, 1 kHz
- frequency memory: none
- Signal processing RF gain, BFO
- Features: Bass/Treble control, digital clock with alarm function.
Power supply
- Mains operation: 110, 220 V
Dimensions
- 340 x 240 (with ferrite antenna 280) x 140 mm, weight 4.6 kg
Accessories
Operation
Similar to the Panasonic portable radios, the Philips AL-990 is a portable receiver, with protective handles on both sides. It's dimensions are 34 x 24 (with ferrite antenna 28) x 14 cm and it's weight 4.6 kg, the cabinet is made of black plastic.
Technically, the set is a double conversion superhet, the shortwave is divided in six ranges and the frequency is displayed digitally with an accuracy of 1 kHz by means of a frequency counter, the frequency processing itself is analog.
On the front panel, the large loudspeaker takes up one third of the area on the left and helps the set to a pleasingly good sound. The controls are arranged in three vertical rows at the right of it. In the row right next to the speaker, there are four knobs and two rotary switches. From below, these are the controls for the volume / AF gain and the separate bass and treble controls. A switch allows to set the instrument to indicate the battery voltage and the signal field strength (S-meter: TUNING), what the third position (POWER) to indicate the audio level can be used for, don't ask me. With the switch above you can select the wide and narrow IF filter, the topmost control is for antenna tuning.
In the middle front panel segment, below the horizontal frequency dials, there is a row of switches. From the left, there is the main power switch, which also activates the alarm clock function, next the dial illumination switch, the switch for buzzer or radio reception in alarm clock operation, the AFC switch for automatic frequency correction in FM broadcast band reception and the BFO switch for single sideband reception.
Above the row of switches is the LCD display, the display can be set to indicate the reception frequency, the local time or the alarm clock time. Above this the analog S-meter, which can also be set to check the battery voltage.
Topmost, there are the quite small coarse frequency dials located, a colored LED marks the currently active band segment. The coarse frequency dial gives you an impression of the location of the tuned frequency in the entire shortwave range. To tune in a station on a known frequency, the dial is much too coarse, but fortunately the set has a digital frequency display.
At the bottom of the right row of controls are the BFO pitch control (the BFO is activated with the switch next to it) and the RF gain control. The large knurled tuning knob is equipped with a fine tuning gear, for a quick frequency change, the knob can be pulled out. After touching the tuning knob, a touch sensor circuit activates the digital frequency display for a few seconds.
Above the tuning knob, there are the band switches: the top one selects the longwave, mediumwave, FM broadcast band and MB (maritime communications band, 1.6 - 4.5 MHz); the lower selects the shortwave ranges SW1 (4.5 - 9 MHz), SW2 (9-15 MHz), SW3 (15-20 MHz), SW4 (20-24 MHz) and SW5 (24-26.2 MHz, this conspicuously short range in a little used band segment makes one think, that there was an international version of the set covering up to 30 MHz).
Other controls include a keypad that folds out from under the speaker to operate the digital clock, and sensor buttons on the top edge to turn off the set for alarm and sleep timer functions.
I'm still a bit lost with the clock functions without the manual, the whole procedure is probably not that intuitive: Pressing the ACTUAL TIME button switches the display to time display, the current time can be stored using STORE (red button on the left) - 1 - 8 - 0 - 5 - S/S (red button on the right). Pressing the DUAL TIME button activates the display of a second time zone, a black triangle appears in the display under the DUAL mark. I then stored the world time UTC with STORE - 1 - 6 - 0 - 5 - S/S. The same procedure is used to store the ALARM time and the SLUMBER timer. When the clock is programmed in this way, the display can be made to show the second time zone (e.g. UTC), the alarm time or the frequency by pressing the small buttons below the digital display and then automatically jumps back to the local time display after a few seconds.
A rotatable ferrit antenna helps to adjust for maximum signal level of a wanted to null out an unwanted signal in the LW/MW range. For shortwave reception, a loop antenna with less directivity can be used. The loop antenna is fixed with a clamping mechanism to the rear panel of the set for transport. For FM broadcast band reception, there is a telescopic antenna.
On the left side of the unit is the 6.3mm headphone jack, on the rear side a tape output, 12 volt and mains socket, a switch for altering the mediumwave IF to prevent interference tones and screw terminals for the connection of SW or FM broadcast band antennas.
The large battery compartment at the rear holds 4 UM-1 mono cells for battery operation and two UM-3 mignon cells for alarm clock functions, there is also some storage space for the power cord.
The operation of the AL-990 is unproblematic despite the abundance of controls. With the power switch in position RADIO-ON the set emits a hissing noise, to receive Austrian Radio Intl. from Vienna on 6155 kHz, the upper band switch is set to SW1-SW5, with the lower switch, select range SW1. On touching the tuning knob the current frequency is displayed and you can tune the receiver to 6.155 MHz. Now the S-meter should read all the way to the right and you should hear the news coming from Vienna; if not, you have to check if the BFO is switched off and the RF gain is set all the way to the right for maximum gain.
With my set of a certain age, a quiet humming occurs when the frequency display is active. There is also some backlash in the tuning mechanism, so that if you overrun a frequency and you tune back, at the first moment nothing happens, and then you overshoot the target again. This circumstance - which does not occur with Collins sets with braced metal gears - and also the frequency drift after switching on are relatively typical for the sets with analog frequency processing and use of a frequency counter. SSB reception is only rudimentary and the use of a RTTY/CW converter with the AL-990 is very problematic.
In summary, the AL-990 was at its time a shortwave receiver with many features, which was not in the top segment in terms of price, but whose reception performance was also only about the price level and made the AL-990 not a top DX receiver, but a useful entry-level tabletop receiver. Thanks to the digital frequency display, the AL-990 helps to reliably identify the frequency of a received station or finding of a station on a known frequency; in the early eighties, this was not at all common for „world band receivers“. Today I consider the AL-990 as an exotic guest in the shack, maybe a useful secondary receiver which reminds me of fourty years ago.
Technical principle
Double conversion (in the shortwave bands only), analog frequency processing with frequency counter.
Components
The set is solid state.
