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Kenwood / Trio - Kenwood Communications, Tokyo

R - 300

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überarbeitet am 21.10.2010

Technically, the Kenwood R-300 is very similar to it's predecessor, the QR-666. It's frontplate has been cosmetically adapted to the consumer's taste of the seventies.

Double conversion, 1st IF 4034 / 2nd IF 455 kHz

Analog dial non linear, accuracy in the mediumwave range around 10 kHz, in the 30 MHz segment only around 100 kHz,
bandspread in amateur bands 80, 40, 20, 15, 10 m (alternative version broadcast bands 75, 41, 31, 25, 19, 16, 13, 11 m)



Selectivity -6/-60 dB

S meter, RF Gain, Noise limiter, Antenna trimmer, Calibrator

The Kenwood R-300 was the first from the R-xxxx series, in contrast to later models, it was equipped with an analog frequency dial only, later sets featured a digital frequency display.

The completely solid state receivers with it's dimensions of 360 x 165 x 300 mm weighs 7.6 kg and comes with a black metal desktop cabinet. In contrast to the grey plastic knobs looking like old mains fuse holders in the earlier QR-666, the R-300 has black knobs with silver metal rims and metal pushbuttons.

In the middle of the front panel, You find the two characteristic green backlit drum dials. The upper one is the main tuning dial with it's tuning knob, below, You find the bandspread tuning dial with calibration marks for the amateur bands.
At the left of the front panel, You find the green backlit signal strength meter and below the pushbuttons for dial lights, the crystal calibrator, the mains power switch and the BFO pitch control.
At the right hand in the front panel, You find a row of pushbuttons for the reception modes (AM and CW/SSB), the noise limiter, a NORMAL/SOFT tone control and the NARROW and WIDE bandwidth filters. Just below, You find the bandswitch and the ANTenna TRIM control, at the right the two rotary controls for RF and AF gain.
The set features an internal speaker at the left side of it's cabinet. At the rear of the set, You find connectors for the antenna, an external speaker as well as the mains and 13,8 V DC connectors. You can control the calibration of the signal strength meter and access some components for alignment of the set from it's top cover.

Operating the QR-666 is quite straighforward: Switch the set on using the POWER pushbutton, turn the RF gain fully clockwise and the AF gain until You hear a slight noise. To receive "Deutsche Welle" on 6075 kHz, use mode AM, band segment D und use the main tuning knob to find the signal from Cologne somewhere between the 6,0 and 6,1 marks. Use the fine tuning control to adjust for maximum readibility and tweak the antenna trimmer for maximum signal strength.
You may make use of the internal crystal calibrator to improve dial accuracy. Set the bandspread dial to it's "noraml" position on 7.0 MHz, switch on the crystal calibrator on look out for the calibrating signal around the 6 MHz mark, tune in for signal maximum. The plexi glass cover with the red calibration line can be moved until it conincides exactly with the 6 MHz mark. Now You habe a better accuracy on the main tuning dial, but make sure, that the bandspread dial is always set to the 7 MHz mark, otherwise dial readings might be very misleading.

In conclusion, Kenwood's R-300 receiver is a simple all wave and amateur band receiver. You can use it for listening to the major international broadcasters signals and for monitoring some amateur radio traffic in CW and SSB modes. Without electronic memories and with it's only rudimentary dial calibration, I would rather recommend a set with digital frequency display for Your first steps on the shortwaves.
From today's point of view, the receiver can be considered as a collector's item that may also be used as a secondary receiver to follow the local 80m band activities.

© Martin Bösch 10.6.2004