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AMATEUR RADIO BY GARRY CRATT, VK2YBX Lowe’s HF-150 general coverage shortwave receiver Lowe’s new general purpose receiver, the HF150, costs less than the flagship HF-225 model yet offers more bells & whistles with the option of computer control & more memories for oftused frequencies. Exactly one year ago, we reviewed the HF-225, a shortwave receiver designed and built in England. Offering superb perfor­ m ance, the receiver also carried quite a hefty price tag, exclud­ing it from the budget of many shortwave enthusiasts. Now, Lowe Electronics has responded to market demands for a lower priced receiver and offer their latest model, the HF-150. Technically similar in many ways to the HF-225, the HF-150 has been designed as an easy to use “little brother” receiver. The unit is best described as a dual conversion super­het receiver, having an inbuilt synchronous AM detector to allow reception of CW, AM and SSB signals. It is amazingly small, having front panel dimensions of 185 x 80mm, and weighs only 1.3kg. A 5-digit LCD shows the receiver frequency, mode and memory number, when the appropriate buttons are pushed. Frequency coverage is continuous from 30kHz to 30MHz. The unit boasts twice the memory capacity of the HF-225, offering 60 user programmable EEPROM memory channels, which Lowe state will retain data for more than 10 years! Little brother to the HF-255, Lowe’s new HF-150 receiver covers the CW, AM, SSB & FM bands over the frequency range from 30kHz to 30MHz. A large LCD indicates the frequency & mode, & there are 60 user-programmable memories. 60  Silicon Chip The unit can be powered from an external DC supply, has external speaker and record outputs, can accept either 50Ω or 600Ω antenna inputs, and offers respectable sensitivity and selectivity figures, almost identical to the HF-225. Identical intermediate frequencies of 45MHz and 455kHz have also been used, together with a combination of IF filters offer­ing bandwidths of 7kHz in the wide mode and 2.4kHz in narrow mode. Receiver tuning is achieved in exactly the same manner as the HF-225; ie, by varying the frequency of both the local and heterodyne oscillators. The local oscillator is a PLL circuit, whilst all other oscillators are crystal derived. A numerical offset is calculated by the controlling microprocessor, so that the display reads correctly, even when the intermediate frequency is offset. Tuning The HF-225 has a series of five pushbuttons to control tuning and memory selections, and a rotary switch to enable the user to select CW, USB, LSB, AM, AMS (synchronous AM) or FM. The HF-150 design has simplified user operations somewhat, so that memories, frequency tuning and receiver mode are selected using only three pushbuttons, operating in conjunction with the liquid crystal dis­play. In addition, the tone control has been deleted. The end result is a clean, uncluttered front panel layout of miniature proportions. In fact the entire unit can be easily held in one hand. The dedicated FM mode has been deleted from the previous design but it is possible to resolve FM using the “slope detec­tion” technique, by tuning the receiver 3kHz above or below the FM carrier frequency. However, some other very convenient features have been added, increasing the versatility of the receiver. Unlike the HF-150, the older HF225 design does not incorporate an RF amplifier stage. This is fine for those of us equipped with long wire or dedicated frequency antennas, but a disadvantage for travellers wishing to use the receiver. To overcome this problem, the HF150 has an inbuilt single stage JFET preamplifier, which is selected by a slide switch on the rear panel. Appropriately marked “whip”, this position is suitable either for the whip antenna supplied in the AK-150 accessory kit for the receiver, or for just a few metres of hook-up wire, often used as a temporary HF receiving antenna by many shortwave enthu­siasts. Another convenient feature not present on the HF-225 is the addition of two battery holders, each carrying 4 “AA” cells. The user manual for the receiver advises that nicad cells will power the receiver for 3-4 hours and can be recharged, whilst remaining in the receiver, in about 16 hours. Alkaline cells can also be used, although they should be removed if the receiver is operated from an external DC source. Remote keypad The HF-225 utilised a combination of pushbuttons for coarse frequency selection and a conventional rotary dial for fine tuning. The HF-150 also offers this method of frequency selec­ tion. However, a far more convenient method is to use the optional remote keypad control. This connects to the rear panel of the receiver, and allows discrete frequencies to be entered directly. This is very useful for quickly checking stations at known frequencies, or for setting the frequency in a particular band of interest and then searching for signals with the main tuning control. The 12-button keypad can be conveniently positioned next to the receiver for ease of operation. Frequencies are entered in kilohertz, by entering the appropriate series of digits and then the “#” key. Because frequencies entered via the keypad are accurate only to the nearest kilohertz, the receiver must be retuned slightly to correctly resolve SSB signals. Computer interface For computer biased amateurs or shortwave enthusiasts, the optional IF-150 RS-232 computer interface allows an HF-150 receiver to be connected to the serial port of any IBM compatible computer or terminal, and provides control of the reception mode and frequen­cy. The RS-232 interface simply plugs into the remote keypad socket on the rear panel of the receiver. Commands to the interface use simple mnemonic instructions and free format numbers, so its operation is straight­forward. Alter­natively, the interface and receiver can be driven from a dedi­cated program, provided this uses the correct protocol. An example program suitable for IBM computers is supplied with the inter­ face on a 3.5-inch 1.44Mb diskette. Control facilities allow remote tuning of the receiver in 8Hz steps, selection of any one of the eight possible reception modes, and recall of the receiver memory contents. Memory down­loading is possible on HF-150 receivers with firmware revision 1.3 or later. A 32-page user’s manual provides details of the various commands used to control the receiver, gives examples of the com­mands used for memory store and recall, and shows how to set the operating mode and frequency. One very pleasing aspect of both the HF-225 and HF-150 is the abundance of technical information supplied with the receiv­er. The user manual include five pages of circuits, while the optional HF-150 Technical Manual gives 38 pages of circuit descriptions, PC board layout diagrams, alignment details, a parts list, disassembly instructions, and enlarged copies of circuit diagrams for the receiver, keypad unit and RS-232 interface unit. The HF-150 has a recommended retail price of $995, which is about 30% less than for the HF-225. The IF150 RS-232 interface is available for $135 (includes the software), while the Technical Manual is available for $49. For further information, contact Emona Electronics Pty Ltd, 92-94 Went­ worth Avenue, Sydney, NSW SC 2000. Phone (02) 211 0988. March 1994  61