INTRODUCTION
The Realistic DX160 is a short wave general coverage receiver, covering 150 Khz to 30 Mhz. It is completely solid state and was made for Tandy in Japan in about 1975. It weighs 15 pounds and cost about $160 when purchased. It can run from 240 VAC or 12 VDC. This is a SWL receiver for first time users.

DX160 Front View

MECHANICAL DESIGN
The cabinet is made from pressed sheet steel which has been plated. The back has a thin wooden panel over it. Inside there are two main printed circuit boards (PCB). One PCB has the RF components on it, next to the tuning capacitor. The other PCB contains the IF and audio components. There is a ferrite rod for local reception, located along the back, behind the wooden panel. The dial stringing and scale pointer cords look complicated. The power transformer is located on the chassis corner. There is some corrosion near the transformer.

The front panel has a long linear dial across the front. There are 5 horizontal frequency scales, and 1 band logging scale. They are different colours. There is a small diamond on each scale, at the amateur radio bands. When the main tunning is set to a diamond, the band spread tuning can be used, and is calibrated in frequency. When tuning the main control, ensure that the band spread is set to the extreme right hand end of the scale, so that the main frequency scale is correct. There are 6 band spread scales, for 3.5, 7, 10, 14, 21 mHz and a CB band. There are other notations on the dial, denoting WWV, Aircraft, Maritime, and Government bands. There is a separate tuning capacitor for the band spread. At the left is the window for the band tuning scale. At the right is the S-Meter.

Below this are four small slide switches. At the left is the noise limiter (ANL) on and off switch. Next is the MODE switch that can select AM or SSB/CW. Next is the AVC on and off switch. At the right is the OPERATE switch which selects RECEIVE or STANDBY.

DX160 Internal View

All the controls are along t he bottom of the front panel. At the left is the phones jack, and then the BANDSPREAD knob, which is a large knob. The next 5 knobs are small. There is the BFO pitch, the AF gain, the ANTENNA trimmer, the 5 position BAND switch, and the RF gain knob. At the extreme right is the large MAIN TUNING knob.

On the back of the receiver, are 3 terminals for a balanced antenna and earth. There is the mains entry cord and a fuse. Then there is a speaker output jack, and a 12 volt DC input socket. At the end is a standby socket.

DX160 Top View

DX160 Speaker

DX160 Circuit

ELECTRICAL DESIGN
The radio uses 1 integrated circuit, 5 FET transistors, 6 transistors, and 15 diodes, located on 2 printed circuit boards.

The antenna uses a tuned RF transformer, to connect to the RF amplifier. This uses a FET with a transistor in the DRAIN to control the RF amplification. The RF gain control adjusts the amount of AVC going to this FET. Reducing the RF gain also reduces the antenna input. The SOURCE has a FET to connect it to the mixer, which is also a FET transistor. The FET transistor RF oscillator is injected in to the mixer drain. The output goes to the IF amplifier.

The IF amplifier uses 2 transistors, and a narrow filter. The first transistor has AVC on its base. The output drives the AM modulator and the AVC amplifier. When switched to SSB and CW, the BFO is turned on, and a balanced modulator is used. This is followed by a transistor amplifier.

There is an Integrated Circuit to drive the speaker and headphones. When switched to AM, the audio comes from a diode in the S Meter and Noise Limiter circuit.

The power supply has a mains transformer, and a diode full wave rectifier, to produce 12 volts DC. This is active all the time that the receiver is plugged into a mains supply. The 12 volts external supply can be connected here. The AF gain control has 2 switches, one turns the DC on and off, and the other turns the AC operated dial lights on and off. The DC goes to a series regulator transistor, to supply a regulated DC to the receiver.

DX160 Rear View

MANUAL
The manual is intended for first time users. It explains the use of the receiver controls. It explains short wave propagation. It has explanations of various signals that may be heard, Government, Aircraft and Maritime. It explains how to tune in CW and SSB stations. It has a list of Morse code signals. It has a list of overseas countries and short wave radio stations. It has a list of Code 10 signals, used by the Police and Fire authorities. It explains the 24 hour clock and World Time Zones. It explains how to convert frequency from megahertz to Meters. It explains how to build an antenna.

PERFORMANCE
This receiver works very well. For a 10 dB signal to noise ratio, the sensitivities are:
Band A: 150-400 kHz 0.7 uV
Band B: 535-1600 kHz 2 uV
Band C: 1.55-4.5 mHz 0.1uV
Band D: 4.5-13 mHz 0.4 uV
Band E: 13-30 mHz 0.6 uV

CONCLUSION
When I acquired this, I thought it was a low quality receiver. I powered it up, and connected an aerial, and was surprised with the sensitivity. I tuned around a little, used the BFO to resolve some sideband signals, and used the band spread control. It tuned very easily, the band spread making it better. The S-Meter worked well. I expected it to be unstable, so I tuned in a CW signal, but it drifted from cold only a little. I guess there is nothing to heat up. As a further test, I banged the top of the case with my fist. It did not drift or shift off frequency. This was surprising. It feels light and cheap, but appears to work well. I do not like the little plastic slide switches, they are stiff and seem flimsy. I would prefer toggle switches. The screen printed labeling has worn off around the switches. The placement of the AF gain control and aerial trimmer are not where I would like them, I always have to search for them. The band spread and main tuning are not precise. The external speaker is very loud. It is a good entry level receiver.The rear wooden panel looks cheap, but this is necessary to allow the ferrite rod to work.

Copyright
Ray Robinson

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