Manufactured by Realistic DX / Tandy Corporation, Fort Worth, FL
With the DX-300, RadioShack / Tandy introduced a decent tabletop all-band receiver in the budget price range in 1979. In contrast to its predecessor, the DX-200, it is equipped with a digital frequency display based on the Wadley loop principle.
- 360 x 165 x 235 mm, weight 6 kg
The set has dimensions of 36 x 16.5 x 23.5 cm and a weight of 6 kg. The power can be supplied alternatively as 12 V DC from a car battery, 8 UM-1 mono cells or mains power: the sets intended for Europe can be powered from 220 V, the US sets only from 110 V AC.
In the middle of the front panel, the red LED frequency display has a central position. The outer ring of the tuning knob selects the MHz ranges, the main tuning knob itself tunes the 1 kHz digits - so you can recognize that the DX-300 is a Wadley loop based set.
To the left on the front panel is the S-meter located, a small FINE TUNING button just below it allows you to detune the receiver by 1.2 kHz, the frequency display is not altered. The preselector dial on the far left has dial marks quite easy to read; depending on the position of the band switch, the corresponding preselector range is indicated with a red LED.
In the lower left corner of the front panel, just below the preselector tuning control, is the preselector band switch. In the VLF range 10 - 150 kHz, the preselector is not active. Next to it are three toggle switches for the attenuator, the dial illumination and an audio filter. Read correctly: the bandwidths WIDE - NORMAL - NARROW of the DX-300 do not refer to IF bandwidths but to the AF frequency response. This attempt to make the listener believe, that the set provided three IF bandwidth filters led to angry reactions and bad reviews among DXers. A little later, RadioShack corrected the mistake, and as expected, the DX-302 has two switchable IF bandwidths.
In the lower right corner of the front panel, below the 12 cm diameter speaker, there is an RF gain control, the volume control combined with the main switch, and the mode selector.
Due to the Wadley Loop technique, the operation is not quite easy, but not too demanding: After connecting an appropriate (not too long) antenna, the receiver is switched on with the volume control, a hiss should be audible. As usual, the RF gain is set clockwise to itzs maximum, the Operation mode switch set to AM. The outside ring of the tuning knob is used to select the MHz band, the tuning knob itself is used to tune the kHz digits, until the display shows the desired frequency. If the signal from Vienna is not yet audible on 6.1 5 5, the preselector - BAND - switch must now be set to position 4.5-12 and the preselector tuned to signal maximum, the marks on the preselector dial give you directions.
The main criticism of the set is the insufficient selectivity: for strong AM broadcast signals, the 6 kHz wide IF filter is quite wide, for SSB reception and especially for CW it is simply much too wide. Even the good sensitivity and the good dynamic range when the preselector is operated correctly do not help.
So the DX-300, which is rarely found in Europe, can be considered a collector's device and representative of an early hybrid radio with Wadley loop principle and digital display; for DXing, it is sufficient for occasionally listening to a strong external service on an undisturbed frequency.
The set is solid state.