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en:dx-190

Realistic DX-190

Manufactured by Realistic DX / Tandy Corporation, Fort Worth, FL.

At the same time as the Alinco SX-190 was introduced, RadioShack sold the set from 1972 on as the DX-190.

Realistic DX-190

Technical data

Power supply

Dimensions

  • 380 x 185 x 245 mm, weight 9.1 kg

Accessories


Realistic DX-190

Operation

The DX-190 is a Double conversion superhet covering nine shortwave broadcast bands in 500 kHz band sections. As an alternative to the version covering the broadcast bands, Alinco also offered the almost identical AX-190, which covers the amateur radio bands, both have two free quartz slots for two additional 500 kHz segments.

The desktop receiver can be operated with 12 V DC or with 115 / 230 V AC, the SP-190 loudspeaker was sold separately.

Realistic DX-190 The set looks like a typical amateur radio with the large main tuning knob in the middle of the brushed aluminium front panel. It has a circular dial with a 0 - 500 kHz graduation and dial marks every 10 kHz. In addition, the tuning knob has a ring with a 1 KHz dial that can be brought to the correct zero position with the crystal calibrator.

To the left of the main tuning scale is the preselector scale, the preselector is operated with a small knob just below it.

To the right of the main dial is the backlit signal strength meter, calibrated in S units. In the lower left corner of the front panel, next to the headphone jack, is the band switch, the set covers the shortwave bands from 60 to 11 m in 500 kHz wide segments. In addition, two crystals for two additional 500 kHz ranges can be installed.

The similar Alinco AX-190 covers the amateur radio bands instead.

Right next to the band switch are the push buttons for the 25 and 100 kHz crystal calibrators.

In the lower right corner of the front panel, the controls for the Q multiplier are located at the top; it can be switched as a narrow-band passband filter or notch filter used to fade out an interfering signal. Right next to it are the RF and AF gain (volume) controls, unfortunately designed as two concentric knobs.

Below that is the mode switch for AM and the upper and lower sidebands in SSB mode, the push button right next to it serves as the main power switch for the set.

On the back of the unit is the SO239 antenna connector and a terminal for an earth connection. Next to the mains cable and the fuse, there is a switch for switching to 12V DC operation and a corresponding DV voltage input socket.

The loudspeaker output is a 6.3 mm jack; a line out signal and the RF and VFO oscillator signals are fed out to RCA sockets.

The DX-190 is a relatively inexpensive double conversion set developed by Alinco, which covers the shortwave broadcast bands. As double conversion is used, the receiver has good dynamic range and excellent sensitivity thanks to the preselector, and the product detector gives the set above-average SSB performance. A disadvantage of the set is that it covers only 500 kHz wide broadcast bands, leaving out most off-band frequencies. The set does not have a digital frequency display or even digital station memories, which makes it more of a collector's set, but it still can be used for real shortwave DXing.

Technical principle

Realistic DX-190 Technically, the RF signal from the antenna input is fed to the first mixer after an RF amplifier stage and is converted to the variable first intermediate frequency of 2420 - 2920 kHz with the signal of a quartz oscillator. After an IF amplifier stage, it is mixed with the signal of the VFO oscillating between 3375 - 2875 kHz to generate the second intermediate frequency of 455 kHz. The mechanical IF filter is connected between two more IF amplifier stages.

After the AM detector, a noise limiter can be activated, for SSB reception a product detector is used and for CW reception the signal of the BFO is added.

After two AF preamplifier stages, the audio signal is fed to the AF output stage.

Components

The set is solid state.

Technical documentation

Development

Further information

en/dx-190.txt · Zuletzt geändert: 2022/12/25 16:49 von mb