- Category: Our Stuff
- Published: Friday, 05 December 2003 00:00
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THE AOR AR7030: A BOLD NEW RECEIVER FROM BRITAIN
As with any receiver, this radio has some quirks and problems here and there. The few that have gotten my attention are described below.
1) The selection of different filter bandwidths or RF attenuation settings causes a brief "pop" to be heard from the speaker or headphones.
2) For those who plan to run the AR7030 from 12 volts instead of the recommended 15 volts, be aware of some anomalies caused by the reduced voltage. On a DXpedition I did some comparisons between 12.5vdc operation and 15vdc, and discovered some subtle but real effects: a decrease in opposite sideband rejection and an increase in digital switching noise at 12.5 volts power. Using the lower voltage, I found that when tuning in USB and approaching a signal from below, a low volume, rising pitch is heard for about 1.5-2 kHz above (past) the center frequency. This effect is reduced 75-100% with 15 volts DC power! I believe this crude test illustrates a degradation in opposite sideband rejection at 12.5 volts. It was interesting to note that a NRD-525 was much worse in opposite sideband rejection at its normal 12vdc power.
At the 12.5 volts level, I found a slight to moderate increase in switching noises, pops, and low buzzes when pushing various buttons. These were all at very low audio levels, but noticeable with careful listening. These noises are virtually absent at 15 volts, except for the brief "pops" when filter or attenuation settings are changed (these are louder and occur irregardless of DC power). Note that these artifacts are only heard during the actual brief moment that the button makes contact when pressed. In the future I plan to run the AR7030 from 15 volts exclusively, for any serious DXing while at home or on DXpedition. I have modified one of my 12vdc DXpedition lead-acid batteries to include 3vdc cells in series/parallel connection to provide the optimum 15 volts.
3) DXpedition use of the AR7030 with Beverage antennas revealed that the preamplifier is needed when listening to extremely weak signals, at or above the noise level under truly quiet conditions. In sensitivity comparisons to a NRD-525 and Drake R-8, the AR7030 equaled the competition only when its preamplifier was activated. (The test signal was Radio Enga, 2410 kHz, during fade-in with audio at 0820 UTC.) Note that the preamp helped intelligibility only for the weakest of signals under quiet circumstances. Another example is my reception and subsequent verification of 2AM Sydney, Australia, on 1620 kHz. This tourist radio station in the Australian expanded mediumwave band runs 400 watts of power. On two different DXpeditions, 2AM's signal was audible without the AR7030's preamp but intelligibility was nil. With the preamp engaged, 2AM improved enough to catch an occasional phrase or sentence (particularly during the second coastal DXpedition).
The typical suburban DXing location has enough local noise and interference to mask truly faint stations, and use of the preamp just raises noise (while reducing 3rd order intercep point, the opposite of what's needed in or near cities). Stated another way, it is my impression that the preamp helps weak signals in a DXpedition environment but not at home where noise levels are higher. I have not noticed any circuit noise increase when using the AR7030's preamp.
4) A receiver of the AR7030's caliber should have more than 100 memories. Serious DXers (especially if they tune foreign mediumwave) can easily make use of 200 or more memory channels. With only 100 memories, an excellent opportunity has been missed to make the AR7030 the receiver of choice for the DXer with many targets across the LF/MW/HF spectrum. The AR7030 memory system is very powerful; it's a shame that only 100 are possible.
The fact that passband shift setting is stored for each memory makes the AR7030 unique among receivers. If 200 or more channels were available, the foreign MW DXer could store LSB, USB, frequency, bandwidth, and passband shift for each split frequency--across the entire band--as appropriate to avoid domestic broadcasters. The exact foreign MW frequency could be stored to step through the memories searching for audio, or the memorized frequencies could be offset (in LSB/USB modes) by a few hundred Hertz to create a heterodyne when a carrier is detected. The receiver's memories can be programmed this way now, but the 100 memories only provide for 900-1000 kHz coverage of the mediumwave band. Stepping through mediumwave with the infrared remote can be done, but the benefits of the AR7030's memories--particularly the passband shift settings--are unavailable.
OPTIONS AND UPGRADES:
An internal battery and fast charger for the receiver should be available soon, and a carrying case for portable use is also planned. Development is underway for a notch filter and noise blanker, although I'm not sure if these two features will be part of the same option or if they will be separate items. AOR is expanding the range of available optional filters, including crystal filters mounted on a special circuit board.
Another planned option is a "VHF Band 2" board with FM stereo capability, to take advantage of the AR7030's two-channel audio path. Eventually, "upgrade" microprocessors will be available, allowing specific capabilities such as "VCR-like" timers for day, week, and year; alpha-numeric labels for memory channels, and other enhanced features.
AOR is also developing Windows-based PC control software for the AR7030, with customized modules for propagation prediction and other related items for the radio enthusiast.
In this age of mega-corporations and design by committee, it is refreshing to see what can be done by a single talented engineer with a vision. Surely, John Thorpe and AOR's UK facility are producing a remarkably useful receiver for the hobbyist and beyond. I wouldn't be surprised to learn of cash-conscious organizations in industry and government choosing the AR7030 over other, more expensive commercial receivers for computer-controlled or remote monitoring. (Rack-mounted Drake R8/R8A receivers have been employed for the same purpose.)
The AR7030 is a very good value and for the money it's a lot of receiver , especially if you live in the USA and purchase direct from England. How willing are you to sacrifice a larger front panel, separate controls and the traditional approach to receiver operation in exchange for high performance, portability, and reasonable cost? It's not easy for long-time DXers, who have strong opinions about "real" radios. Will this receiver become a DXer's workhorse or languish on retailers' shelves as a collectable curiosity? AOR management will readily know our consensus answer to this question, when they study sales figures in the years ahead.
THE KIWA POCKET LOOP ANTENNA
This is another clever accessory from Kiwa Electronics that makes me wonder why didn't I think of that?! While it won't fit in your average shirt or pants pocket, it can be tucked neatly out of the way in a large coat or parka.
The Pocket Loop is an air-core antenna designed to improve reception of portable receivers. The antenna elements are made of copper-coated spring steel wire, otherwise known as "piano wire". Collapsed the loop measures 4" x 5" x 3", but it will easily pring to life a full 12" in diameter. The wire elements have sufficient tension to support themselves, yet are flexible enough to collapse--again and again-- into a compact package for transport. The entire assembly appears sturdy enough for many years of regular use.
Signal transfer to the receiver is done by a special coupler, or by a direct cable connection. The coupler is for portable receivers having a shortwave whip antenna, and/or an internal ferrite bar antenna. The coupler is placed against the outside of the receiver case (Velcro fasteners provided), near the ferrite bar antenna, or over the end of the whip if shortwave enhancement is desired. The supplied direct cable is used with communications receivers having a high-impedance (hi-Z) antenna input. The Pocket Loop cannot work with a 50-ohm antenna input.
The antenna's front panel tilts forward for easy operation and access to the tuning range switches (small "DIP" switches). Power requirements are very low at 12 ma via a 9vdc battery, so the loop should run a long time before a battery change is needed. Frequency coverage is from 530 kHz through 23 MHz in four ranges of 530-1800 kHz, 1.8-7 MHz, 5-20 MHz, and 18-23 MHz. The antenna has a built-in "noise generator" to aid in the tuning of signals, and this feature really adds to the easy operation of the Pocket Loop. The loop's internal amplifier is quiet and has good gain, while the sharp tuning helps the loop resist overloading.
I have used the loop with a GE Superadio II for mediumwave, and an AOR AR7030 for shortwave and mediumwave reception. The results were very good with both receivers, and an added bonus is the capability to null local noise sources by careful positioning of the Pocket Loop. On almost all shortwave signals, the loop outperformed a 45 ft. long randomwire antenna, but couldn't compete with the "serious" outdoor antennas I use for tropical band DXing (an unrealistic expectation for a small portable antenna!). For mediumwave when using the special coupler and the Superadio II, the difference was sometimes dramatic. Signals I could barely hear at all with the ferrite rod antenna became easily readable at good signal levels with the Pocket Loop.
Go to Chapter One
We thank the Ontario DX Association as the original publisher (August 1996 DX Ontario bulletin).