Inhaltsverzeichnis
Kenwood R-300
Manufactured by Trio-Kenwood.
Technically, the Kenwood R-300 is very similar to its predecessor, the QR-666, but the front panel was cosmetically adapted to the requirements of the mid-seventies.
Technical data
- Frequency range LW (170 - 410 kHz), SW (525 - 1250 kHZ), 4 x SW (1.25-3 / 3-7.5 / 7.5-18 / 18-30 MHz), spread ham bands 80, 40, 20, 15, 10 m (alternative version spread broadcast bands 75, 41, 31, 25, 19, 16, 13, 11 m).
- Frequency display: Analogue display, not linear, in the MW range accuracy of around 10 kHz, towards 30 MHz only 100 kHz can be estimated.
- Frequency memory: none
Power supply
- Mains operation: 117, 220 V; 13.8 V =
Dimensions
- 360 x 165 x 300 mm, weight 7.7 kg
Accessories
Operation
The Kenwood R-300 was the first receiver from the R-xxxx series and, in contrast to the later sets, had only an analogue frequency dial, the later sets all came with digital frequency displays. The fully transistorised all wave receiver has dimensions of 36 x 16.5 x 30 cm and has a black metal cabinet. The control elements were adapted to the taste of the time, instead of the controls of the QR-666, which were reminiscent of screw in fuse holders, the R-300 has black buttons with silver accents. On the one hand, the frequency setting is done with a coarse tuning dial, on the other hand, frequencies in the amateur radio bands can be set more precisely on a band spread dial.
The front panel is dominated by the two horizontal drum dials with the tuning knobs next to them.
On the far left of the front panel, below the S-meter calibrated in S units, are the push-buttons for dial illumination and the crystal calibrator, below that, still on the far left, is the main switch, next to it the BFO control for single sideband reception. A headphone and a tape recorder can be connected to the jacks in the left lower corner of the front panel.
The upper dial covers longwaves, mediumwaves and, in four segments, the entire shortwave range up to 30 MHz. On the lower dial, the spread amateur radio bands can be tuned with the tuning knob next to it. There was a variant of the receiver advertised that had bandspread broadcast bands instead of the ham bands.
To the right of the drum dials is the row of buttons for the operation modes, AM or CW/SSB (for SSB reception a BFO is switched on, the BFO control to the left below the dials is used to set the beat tone or the sideband). The other controls operate the noise limiter ANL, the tone control and select the wide or the narrower IF filter. To the right of the mode switches is the RF gain.
The range switch below the mode buttons selects the band segment from longwaves, mediumwaves to the four shortwave ranges. At the right of the bandrange switch is an antenna trimmer and at the bottom the volume control (referred to as AF gain).
A loudspeaker is built into the left-hand side of the receiver. At the rear of the set are the terminal connectors for long-wire antennas, the mains power supply and for 13.8 V DC for car battery operation, and the jack for an external loudspeaker. At the top, some adjustment elements are directly accessible from the rear of the unit; similarly to the 9R-59DS, the S-meter sensitivity can also be adjusted.
Now to the operation: After switching on with the mains switch at the bottom left, the RF gain control is turned up fully, then the AF gain is set to a medium hiss. To receive Radio Österreich International on 6155 kHz, select Operation mode AM, set the bandrange switch to D and search dial D between the 6.1 and 6.2 MHz marks. When the news from Vienna become audible, the fine tuning can be used for optimal tuning and, if necessary, the antenna trimmer to peak for maximum signal.
When the crystal calibrator is activated and the lower bandspread dial is set to 7.0 MHz, the signal of the crystal calibrator can be tuned at 6.0 MHz an be adjusted to maximum S-meter deflection. The plexiglass dial window with the red pointer line can then be carefully moved until it exactly coincides with the 6.0 MHz mark and from there the frequency can be better adjusted. If the lower fine tuning dial is in a different position, the receiver may receive on a completely different frequency than the one shown on the main dial.
Since the R-300, unlike its successors, does not have a digital frequency display, you have to know the stations active in the shortwave broadcast bands pretty well to identify a station, otherwise you have to wait for the station announcement and hope that the local African station you are looking for does not turn out to be the French service of Voice of Russia.
In summary, the Kenwood R-300 can still be used as an all wave receiver for search reception on the shortwave bands and allows the reception of many an exotic station, even amateur radio operators can be heard in CW and SSB. Without digital memories and with only rudimentary possibilities to determine the frequency of a received station, a set with digital frequency display is much more recommended to enter into shortwave reception.
Technical principle
Single conversion superhet with bandspread dials for the amateur radio bands.
Components
The set is solid state.
