Equipment Reviews, October 1998
The AOR AR7030 Plus/NB7030 Receiver
One of the things that I really like about the AOR AR7030 receiver are the extensive number of options that are available to customize the receiver for a particular type of listening. AOR has added even more options with the release of the “Plus” version of the ‘7030, the FPU7030 microprocessor upgrade and the NB7030 noise blanker and notch filter.
The AR7030 Plus has modifications made to various stages to improve the receiver’s dynamic range and lower synthesizer noise. These changes include improved mixer balance for higher intercept performance, high tolerance components in the direct digital synthesis circuit for lower noise, enhanced attenuator performance for lower intermodulation distortion and a higher specification antenna input transformer to lower mixing products. The “Plus” has a 4 kHz metal-case ceramic filter installed in place of the 7 khz filter in the standard ‘7030 — this nicely fills the bandwidth gap between the 2.2 kHz SSB filter and the 5.5 kHz AM filter. One other component change is the use of a higher quality encoder for smoother tuning. The “Plus” has the enhanced CPU, (but not the notch filter/noise blanker) which I will describe separately, since it is available separately for the standard ‘7030. The AR7030 Plus costs about $250 more than the standard receiver.
The most noticeable benefit to the “Plus” package to my ears was the 4 kHz filter. It is a definite benefit for listening in severe interference situations. The passband shift control allows for setting the filter curve for maximum intelligibility while reducing adjacent channel interference. I could detect no difference in casual listening from the front-end upgrades in the Plus — there were no spurious responses above or below the MW band from strong local stations on either version of the radio. There was also no significant difference between the tuning of the two radios.
FPU7030 Enhanced CPU
The FPU7030 is a replacement microprocessor and EEPROM that increases the memory capacity of the ‘7030 from 100 channels to 400. Memory scanning is supported but only in blocks of 100 channels maximum. The FPU7030 also permits attaching a 14 character alphanumeric label to each of the memory channels. Labeling is performed by selecting characters with the front panel “spin” knob. Numbers, both small and capital letters and a variety of symbols can be selected for the labels. A “cut and paste” feature is available for labelling multiple memory channels. The label is displayed as each memory channel is selected or if the radio is tuned to a frequency that is stored and labeled in a memory channel.
The FPU7030 also provides greatly expanded timer capabilities for unattended operation. The number of timers is increased to 10 one-year timer memories. From my reading of the instructions, the timer cannot be set to turn on at weekly intervals, i.e. the date must be set for each timer-on event. The standard 24 hour timer of the standard ‘7030 is still available for use, even with the FPU7030 installed.
The FPU7030 provides the software support for adding the NB7030 noise blanker/notch filter. The FPU7030 has a U.S. street price of $120.
NB7030 Noise Blanker/Notch Filter
The NB7030 is a add-in circuit board that adds an impulse-type noise blanker and notch filter to either the standard ‘7030 or the Plus. The noise blanker works in the RF stages to reduce pulse type noise from automobile ignitions, etc. It is not the DSP type of noise reducer that can work on hiss, static and white noise. The width of the blanking pulse can be set for narrow or wide and the trigger threshold for the blanking pulse is adjustable. The notch filter works in the audio stages and is tunable over the range of 150 Hz to 6 kHz. The filter can be manually or automatically tuned and provides an attenuation of greater than 40 dB. Unlike some of the outboard DSP notch filters which can notch heterodynes on multiple frequencies, the NB7030 provides only a single notch frequency. The U.S. street price for the NB7030 (including the FPU7030 which is required for support of the NB7030’s functions) is $299.95 - $239.95 for the notch and noise blanker alone, if one is upgrading a ‘7030 Plus or a 7030 which has already been modified with the enhanced CPU.
Adding the notch/noise blanker requires selecting their respective configuration settings on the setup menu. Adding these options (as well as the other features of the enhanced CPU) increases the number of branches in the control menus. The notch controls are accessed from the main “Filters” menu, while the noise blanker is accessed via the “RF-IF” main menu. The “Tone” and “VFO” menus are now branches off the “Notch” and “NB” menus, respectively. It adds a bit of complexity to an already complex user interface.
The notch filter works like a champ. The easiest way to use it is in auto tuning mode, which is enabled by turning on the notch and pressing the “Search” key. The notch circuit sweeps from 300 Hz to 6 kHz and automatically stops on the lowest frequency steady signal in that range. I found it to be quite accurate and effective. Using the notch allowed me to “open up” the bandwidth for maximal fidelity but eliminate the 5 kHz whistle from adjacent stations. The notch is narrow enough that notching the heterodyne has minimal effect on desired signal content. The notch can also be manually tuned via the “spin-wheel”. The tuning rate is automatically slowed when the notch frequency approaches that of a steady signal. The notch is such a useful feature that it should be included as standard.
Unfortunately, the noise blanker is less useful. As a standard pulse-type noise blanker (i.e. effective on impulse noise such as that from automotive ignitions), it works well, but the majority of noise that I am plagued with is not of that type.
Too Many Choices?
The question now becomes which version of the AR-7030, with which options should one buy? For those with unlimited budgets, the answer is the ‘7030 Plus with the noise blanker/notch option with a total price of just under $1500. For those who do have to watch the bottom line, the answer depends on one’s primary type of listening. The nice thing about the Plus version is the addition of the the 4 kHz filter for DX’ing. However, a standard ‘7030 can have a 4 kHz Murata ceramic filter added for an additional $45 or a Collins mechanical 4 kHz filter can be added for $120. Adding the notch/noise blanker along with a 4 kHz ceramic filter to the standard ‘7030 gives a package price of about $1350. Other filter bandwidths are available for CW or data modes.