Equipment Reviews, February 1997
The AOR AR7030 General Coverage Receiver
I cannot remember a receiver in recent times which has been greeted with so much controversy at its introduction. The manufacturer’s published specifications were called into question and whether or not the radio’s operating system was designed for use by mere mortals was a point of contention. However, as owners and reviewers have gained experience with the receiver, it is now being praised as offering an excellent combination of performance and value, and was selected as the “Best Tabletop Receiver 1996/1997” by the World Radio TV Handbook.
Origins
AOR is a well-known Japanese manufacturer of UHF/VHF scanners and wide-band receivers. A few years ago they entered the HF only market with the AR3030 receiver, which I have not had the opportunity to review, but reportedly offered decent performance at a reasonable price. AOR UK was initially set up as a distribution arm for AOR (Japan), but AOR UK’s director of sales developed the concept of the AR7030 and AOR UK became a manufacturing concern.
The AR7030 was designed by John Thorpe, who was responsible for the ground breaking “HF” series of receivers from Lowe (through the HF225 Europa). The new receiver was to be transportable, provide “open” architecture to permit upgrading, provide exceptional strong signal handling performance and be reasonably priced. The result is the AR7030.
The Externals
The AR7030 is a radical receiver, both internally and externally. The case is heavy cast aluminum finished in black with gently rounded sides. The dial escutcheon is curved at the end closest to the tuning knob and flares as it approaches the knob, yielding a very “dynamic” appearance. The control layout follows the minimalism of previous Thorpe designs, with three rotary knobs and nine pushbuttons. Most of the pushbuttons and one of the knobs have varying functions, depending on what menu choices have been made in the operating system. The controls that are dedicated to a single function are the power switch, the fast tuning and mode buttons (arrayed in an arc above the tuning knob) and the tuning knob itself, which is a heavy cast unit with a “spinning” dimple. To steal a line from the automobile commercial–“This is not your father’s Hammarlund!”
On the back are the antenna connectors–a SO-239 for coaxial cable or a whip and spring clips for a high impedance wire. There are two DIN sockets: one for computer control and the other for tape recorder activation, line level audio, mute and IF out. The back panel also has connectors for the outboard power supply and an external speaker.
The overall size is 9.4 x 3 x 8.9 inches (WxHxD) and the weight is 4.8 pounds. The external “brick” power supply puts out a regulated 15 volts DC at 800 mA.
The Internals
The AR7030 has been designed for excellent strong signal capability and low oscillator noise. It is a dual conversion design with intermediate frequencies of 45 MHz and 455 kHz. Frequency coverage is from 0 to 32 MHz and sensitivity in the medium wave region has not been deliberately reduced. The tuning is synthesized and uses a TCXO (Temperature Compensated Crystal Oscillator) frequency reference for stability and single-loop Direct Digital Synthesis for low phase noise. The phase noise specification is <-158dBc/Hz @ 100 kHz spacing. The synthesizer tuning steps are 2.655 Hz in SSB/CW/DATA modes and 10.62 Hz in AM/NFM.
The receiver’s resistance to overload and distortion from strong signals is due to the use of relay switching instead of diodes in the front end, use of shielded inductors and a lateral DMOS FET QUAD first mixer running at 15 volts. (The radio can be run from a DC power source of 12-15 volts with slightly degraded performance.) The claimed dynamic range specification for the 2.2 kHz filter with a signal spacing of 20 kHz is 104 dB with a third order intercept point of +32 dBm. The blocking dynamic range is 137 dB. This was another area of controversy, as Radio Nederland’s testing showed a third order intercept point of 0 to 2 dBm at 200 kHz spacing–not an exceptional figure. The manufacturer’s claimed specifications have since been confirmed by several other independent reviewers, both in the U.S. and Europe. Some reviewers found that the performance of the AR7030 pushed the capabilities of their test equipment to the limit! The discrepancy in the test results are due to differences in testing methodology, according to the review in the 1997 World Radio TV Handbook.
DXers will really appreciate the IF filtering capabilities of the AR7030. Four filter bandwidths are standard: 2.2, 5.5, 6.6 and 9.5 kHz. These are followed by “tail” filters which permit the use of reasonably priced ceramic filters without compromising ultimate selectivity. There are spaces on the main PC board for two additional filters, which can be just about any type of filter having a 455 kHz center frequency. Holes are pre-drilled on the board for a variety of filter sizes (there are even solder pads for replacing the standard filters, except the 9.5, with higher quality ceramic units). This capability allows the user to tailor the IF bandwidth response to whatever is best for their particular type of listening. Optional filters that available through AOR are Collins mechanical filters of nominal 0.5, 2.5, 4.0 and 6.0 kHz bandwidths, Murata ceramic filters of 1.0, 3.0 and 4.0 kHz bandwidths and a crystal filter of 2.4 kHz. A separate daughterboard is recommended for installing crystal filters. KIWA filter modules could also be used. The unique feature of the AR7030’s filtering (at least for receivers in this price class) is that the radio self-aligns to optimize filter performance. What this means is that the radio generates a variable frequency signal which is passed through the filter and the radio’s computer determines the filter’s bandwidth, center frequency, slope response and injection frequencies for proper USB/LSB reception. Once the filter’s calibration characteristics are determined, the receiver can adjust the frequencies of its various oscillators to maximize each filter’s performance.
Operating System
One element of the AR7030 that has produced a great deal of comment is the operating system. The AR7030 has almost all of the bells and whistles that are expected of modern communications receivers: dual VFO’s, memory channels (100), selectable AGC, passband shift, synchronous detection, squelch, timer operation, etc., but the radio has just a few buttons and knobs to control all of these features. The knob and button count was kept low to maintain the designers’ objectives of compact size and affordable pricing. The solution taken by the AOR designers was to set aside a rotary control (referred to as the “spin wheel” in the operating manual) and a pushbutton (“General button”) to control various functions. The function assignments are made by selecting from menus brought up by the other front panel pushbuttons. For example, if the “Filter” menu is selected, the spin wheel becomes the Passband Shift control and the general button is used to step through the filter selections. Some of the other possible spinwheel/general button assignments are IF gain/AGC speed, Squelch level/VFO swap, Memory channel/Channel recall, PBS/BFO offset and Squelch level/Scan Start/Stop.
Sounds complicated, doesn’t it? In all honesty, I was able to use the receiver straight out of the box without referring to the manual for basic DX’ing. I did have to study the manual to understand how to use the memories, scanning and clock/timer. It does take a bit of getting used to, but the manual is well-written and the system is easily mastered with just a bit of practice. I found the spinwheel/button arrangement to be ingenious and quite logical after I got used to it. For DX’ing, I would use the PBS/Filter combination for interference rejection. If I was primarily program listening, I would select the tone control assignment. For checking my “hit list” stored in memory, I would switch to the Memory select/recall combination.
The Setup Shortcut
There are three global setup receiver memories that are available at intial power-up. These memories save desired settings of filter bandwidth, AGC, passband shift, BFO offset, etc. This permits setting up the receiver for a particular type of reception, such as RTTY, and being able to return to that configuration without stepping through the menus to reset all of the receiver’s parameters.
The Arm Chair Approach
All of the above discussion becomes rather moot if one decides to control the receiver via the included wireless remote control. All of the receiver’s functions with the exception of AGC speed, BFO offset and IF gain are available via the remote. The tuning step of the Up/Down tuning buttons on the remote can be set to any value between 2.7 Hz and 50 kHz. I set the tuning step to 5 kHz and used the remote to bandscan while using my computer, which is located about 6 feet away from the receiver. The remote can be used for direct frequency entry in either MHz or kHz format or for memory channel selection. The remote will operate the receiver at a maximum range of at least twenty feet, but I couldn’t read the display at more than six feet away. The infrared sensor seems to have a wide angle of response–I was able to utilize the remote with the controller flat on the desk, just a few inches away from the receiver, even with the receiver’s tilt bail extended. This avoids having to use the remote with two hands for up-close operation. The receiver has infrared sensors on both the front and rear panels, for flexibility in receiver placement. I did notice that the receiver won’t accept entries from the keypad while the sync mode is in the process of locking. The receiver can not be turned on or off via the remote and a Mute function to immediately silence the radio would be a nice feature to add to the remote.
Performance
I think the AOR AR7030 is a great receiver–I was particularly struck by how quiet it is. I think that this is due to the excellent strong signal handling capability that helps to reduce intermodulation products that tend to raise the noise floor and the Direct Digital Synthesis frequency synthesis that reduces phase noise. Sensitivity was excellent with an outdoor antenna–I didn’t test the radio with any type of indoor or active antenna.
Filtering
Selectivity is good, although I would like to see a different selection of stock filter values. The nominal IF bandwidths that are supplied with the receiver are 10, 7, 5.5 and 2.2 kHz–in the review receiver, the self-alignment program measured them at 9.5, 6.6 , 5.5 and 2.2 kHz. For SWBC DXing, I like to have a filter of approximately 4.0 kHz available and some DX’ers like to have an additional narrow value in the range of 3.0 kHz. In all fairness to AOR, nearly all communications receivers suffer from this bandwidth gap, being fitted with a 6 kHz filter for AM reception and an approximately 2.4 kHz filter for SSB. The good news is the AR7030’s capability to accept a wide variety of optional filters, as previously noted. Several different optional filters are available from AOR, although it appears that these are more readily available in Great Britain than in the U.S.–I requested that the review unit be fitted with a Collins 4 kHz filter (which the receiver measures as 3.6 kHz) and the radio had to come from England.
The filter skirt selectivity is excellent. I tended to use the 5.5 kHz filter for program listening and occasionally the 6.6 kHz filter if the station was in the clear, although there was usually an audible heterodyne with the 6.6 filter, which was knocked out by switching to the 5.5 value. For tougher signals, the 3.6 filter was great for listening in either the AM or sync modes. For really tough catches, I would switch to the 2.2 filter and listen in either USB or LSB. The passband shift control was very effective in shifting the filter’s “sweet spot” for greatest intelligibility. The 9.5 kHz filter is included for narrowband FM reception–a mode that is sometimes used by hams above 29 MHz and for Citizen’s Band services in some countries. It could also be used for reception of MW signals with little interference. I couldn’t tell much difference in the sound between the 6.6 and 9.5 kHz filters–perhaps the overall audio frequency response is the limiting factor here.
Audio Quality
This is one of the best sounding radios that I have used in a while. There is a top mounted 3.5 inch speaker which is good, but even better sound is achieved by using an external speaker. The audio output amplifier supplies 2.2 watts into an eight ohm load. Total Harmonic Distortion (THD) is rated at 0.2% in SSB modes and <1.3% for AM modes which are outstanding specs for a communication receiver. The tone controls are very effective in shifting the tonal balance of the received signal due to the chosen turn-over points of 200 and 2000 Hz.
My only complaints about the audio of the AR7030 concern the headphone output. The jack is a 1/8 inch stereo jack, which is fine for Walkman type headphones, but most headsets designed for communications applications have a 1/4 inch plug. In addition, the output level through the headphone jack is very low, requiring that the volume control be advanced to about 80% of full rotation. Using headphones of differing impedances had no effect on this phenomenon. There are separate amplifiers for the speaker and headphone outputs, so I assume that the level of the headphone amp has deliberately been set lower. One other disquieting discovery concerning the use of headphones with the ‘7030 is that when the sync detector is in use, there is sometimes a repetitive “click” audible in the ‘phones. I couldn’t hear this in an external speaker, but could when the external speaker output was used to drive an amplifier.
Users of outboard decoding devices, recorders, etc. may be interested to know that there are two independent line level outputs, whose levels can be set independently and can be muted by the squelch control. There are two sets of relay contacts for controlling tape recorders–the relays can be activated either by the single-event timer or by the squelch.
AGC/Sync
Good audio in a receiver is determined by much more than just the audio amplifier. The automatic gain control, which serves to smooth out variations in the receiver’s volume as the signal level fades, is one of many determinants of how a radio sounds. The AGC in the AR7030 is excellent. Three decay rates (Fast, Medium and Slow) as well as AGC Off are selectable. There are separate attack rates for AM and SSB modes. The AGC action is very stable and is free of “pops” and overshoot. The AR7030 produces some of the smoothest SSB reception that I have heard in a long time.
Synchronous detection has been a major advance in the past decade in improving the quality of shortwave broadcast reception. Synchronous detection reduces the distortion caused by the phenomenon of selective fading, in which the levels of the sidebands of the signal relative to the carrier vary due to propagation. The ‘7030 has an intelligent sync detector which automatically fine-tunes the receiver to the carrier frequency of the signal. This process takes a second or two to occur and the receiver mutes while the sync is locking. The detector will track the crrier if the station should drift. Sync mode will automatically deactivate while the tuning knob is being rotated but will reactivate when tuning is completed. The manual states that the tuning accuracy of the automatic sync is to within 100 Hz (typically 30 Hz) of the actual carrier frequency. The automatic tuning feature can be defeated, in which case the operator must tune the receiver to zero beat for the synchronous detector to lock properly. In manual mode, the display will indicate in which direction to tune if the receiver is not tuned close enough to the carrier frequency for lock to occur. Detector calibration is bypassed in manual sync mode and the frequency display may not indicate the exact carrier frequency, although the signal is tuned to zero beat. The AR7030’s synchro is one of the most tenacious I’ve encountered. I never heard it lose lock when in the Automatic sync mode, although it did occasionally when in the “wide” manual mode. On the ‘7030, sideband selection in sync mode is done via the Passband Shift rather than the switching arrangement on some other receivers.
Is It Really That Hard To Operate?
This is a highly personal question, but let me try to give a “real-world” example of how I use the radio. I usually use the keypad to enter a frequency and then use the radio’s front panel controls for the other functions. Once power is on (which can’t be done via the keypad), the green LCD display shows the time in 24 hour format with seconds, the frequency to a resolution of 10 kHz, mode and a linear bargraph S-meter display. I should add here that the S-meter markings are printed on the panel below the LCD display in tiny type and are essentially illegible at a distance greater than 12 inches. From here I would typically choose the “Filter” menu to select the desired IF bandwidth. Then I could press the “Menu” key which returns the display to the S-meter, with the spin-wheel assigned the passband shift function and the general button used to carousel through the IF bandwidths. I would then typically use the “Mode” pushbuttons to go to Sync mode. I might then go back to the “Filter” menu, choose the “Tone” sub-menu and adjust the Bass/Treble through the spin-wheel and general button. Hitting the “Menu” button then goes back the base display and I could then press the “RF-IF” key to adjust the IF gain, AGC, attenuation or go to the VFO sub-menu. I found the operating system to be quite intuitive after just a little practice, but it is a matter of personal taste.
I didn’t do much with the scanning system, but it appears to offer a lot of features. The AR7030 scans the memory channels in any range from two to the receiver’s maximum of one hundred channels. The operator can set the delay time, hold (if the channel is active), mute, etc. The ‘7030 cannot scan between two selected frequencies, unlike some other receivers. The radio can also be configured to switch between the two VFO’s, with the same definable parameters as the memory scan. I found this to be very handy, as I could set a long delay time to actually listen to a program on one frequency and then have the radio briefly switch to the other VFO to check for activity on a particular frequency.
I also didn’t do anything with the computer control facilites of the AR7030, as I didn’t have any software to control it with. I am not aware of any domestic control software for the receiver. AOR UK informed me that a program named “Data Master” is available, but, like the optional filters, this appears to be more readily available in the U.K. than in the U.S.
Overall
I think that the AOR AR7030 is a “state of the art” radio for any type of communications monitoring. It is an outstanding performer and can be configured for optimum reception of any type of signal, be it voice, music, data or Morse code. The price is very competitive, with a street price that is $100 more than a Drake R-8A and about $500 less than a Japan Radio NRD-535D. There is one potential hidden cost with the AR7030, however, and that is the filter gap between the stock 5.5 kHz and 2.2 kHz values. The Collins 4.0 kHz unit fills this gap nicely, but adds about $80 to the cost of the radio. There are some lower cost Murata ceramic units available according to the info sheet from AOR UK, but they don’t seem to be readily available in the U.S. This filter gap and the size of the headphone jack are the only things that I would change in the AR7030. There are plans to produce an audio notch filter/RF noise blanker board along with CPU upgrade to permit expanded memories with alphanumeric labeling. This should be available in early 1997. The U.S. AOR distributor is EDCO, 325 Mill St., Vienna, VA 22180; (703) 938-8105. AOR UK can be contacted by E-mail at: info@aor.co.uk and their Website can be found at: http://www.demon.co.uk/aor/.