THE RADIO SHACK PRO-2006 PROGRAMMABLE SCANNER
by Bob Parnass, AJ9S
The Radio Shack PRO-2006 is a 400 channel, wide coverage
scanner radio, manufactured in Japan by General Research
Electronics. It is the successor to the PRO-2005 and a
grandchild of the PRO-2004, the super scanner which put
Radio Shack out in front of its competition in the base sta-
tion scanner market.1
The PRO-2006 is almost identical to the discontinued PRO-
2005, with the exception that the PRO-2006 boasts
HyperscanTM, a catchy way of saying that it scans fast --
about 26 channels/second versus the PRO-2005's 16
channels/second rate.2 At about $400, the PRO-2006 is $20
cheaper than the PRO-2005 was. Both scanners are built
using surface mount components and are housed in a gray
The PRO-2006 covers 25-520 and 760-1300 MHz, except for 2
gaps in the cellular telephone bands. The two gaps in the
800 MHz range can be restored all the Radio Shack continuous
coverage scanners by removing a diode. Diode D502 is the
culprit in the PRO-2005 and PRO-2006.
A matrix of diodes, attached to the microprocessor's input
port, is often used to configure radios for sale in dif-
ferent markets. The diode matrix on new the PRO-2006 is
located on the vertical circuit board just behind the front
panel. There are 2 diodes present, and holes drilled for 2
Lots of Memory
The PRO-2006 has the usual features that scanner buffs have
come to expect: individual channel lockouts, selectable 2
second rescan delay, an external speaker jack, etc. Casual
scanner users don't need 400 channels, but scanner hobbyists
can have those channels filled up in no time flat, espe-
cially with frequencies in the vast 225-400 MHz military air
band, and other federal government allocations.
With so many channels to program, one dreads the thought of
a power failure, which could clear memory in a hurry. Not
to worry, the PRO-2006 memory is backed up by a conventional
9 volt alkaline battery (not supplied), which should be
replaced every 6 months or so.
The 400 channels are divided into 10 banks of 40 channels
each, and one can select or deselect any channel bank from
the scan list. Individual channels can be locked out in the
customary way, but the PRO-2006 maintains the handy feature
introduced in the PRO-2004, a LOCKOUT REVIEW. Successive
depressions of this key step through the locked out chan-
Scanners worth their keep have a priority feature, with
channel 1 usually designated the priority channel. The
PRO-2006 is more flexible; any of the 400 channels may be
designated the priority channel. When the PRIORITY key is
depressed, that channel will be sampled every 2 seconds, and
the radio will stay there if a signal is heard.
The PRO-2006 has two scan speeds, which measured approxi-
mately 13 and 26 channels/second. While scanning at high
speed, the PRO-2006 won't skip over weak signals like some
of the AOR-2515 scanners do. Adding diode D501, situated at
an unmarked location between D502 and D503 sped up the PRO-
2005 scan and search rates by 25%. Adding the same diode in
the PRO-2006 has no effect on the scan or search rates.
It has been claimed that a PRO-2005 could be made into a
PRO-2006 by merely replacing the CPU clock crystal with one
of a higher frequency. Don't believe it. Changing the
PRO-2005 clock speed would affect both the rescan delay and
the priority rate, and they would no longer be 2 seconds
long, as they are in the PRO-2006.
When programming a channel, the PRO-2006 firmware sets the
mode automatically, based on its idea of what mode is most
prevalent on that frequency. This feature saves extra keys-
trokes, and makes one appreciate the thought that went into
the design of this radio. The default mode can be overrid-
den easily, if need be, like to listen to a military mid-air
refueling operation in the 225-400 MHz range, which is
mainly populated with AM signals.
The SEARCH facility found on most programmable scanners
allows the entry of a pair of frequencies, then by pressing
a key, the radio searches frequencies between those limits.
The PRO-2006 allows for 10 pairs of limits! These pairs of
limits are stored in their own memory, and don't use up any
of the conventional 400 memory channels. One can set up
several search pairs, for instance:
- 46.610 - 46.970 MHz: cordless telephones
- 144 - 148 MHz: the 2 meter ham band
- 418.625 - 418.900: Drug Enforcement Administration
Another unique feature of the better Radio Shack models is
the MONITOR key, which stops the search and stores the fre-
quency in one of ten special monitor memories. These
memories are separate from the 400 main memory channels.
The search can be restarted from where it left off by strik-
ing the up or down arrow key.
The user can select the search direction (up or down), and
step size of 5, 12.5, or 50 kHz, although the PRO-2006 is
intelligent enough to select a default step size based on
the frequencies being searched. As on the PRO-2004 and
PRO-2005, there is a hidden step size of 30 kHz, but this
step size is only used in the cellular phone band after res-
toring full 800 MHz coverage.
The selected parameters are displayed on the LCD panel,
smaller than the panel in the PRO-2004.
The DIRECT key allows one to start searching up or down from
whatever frequency is on the display. Let's say the scanner
is in MANUAL mode, and set at channel 26, which contains
460.100 MHz. Striking the DIRECT then UP-ARROW keys starts
the PRO-2006 searching upwards from 460.100. This is a nice
The PRO-2006 contains a "window detector" circuit, which is
called into play during a SEARCH operation. This circuit
tries to detect when the radio is tuned close to the center
frequency of a station, and prevents the search from halting
prematurely, off to the side of the signal.
The AFC (automatic frequency control) circuit of the Bearcat
800XLT often causes a search of 850 MHz signals to halt
prematurely. Even though the signal sounds on frequency,
the display reads the wrong frequency. Neither the PRO-2004
nor the PRO-2006 have this problem.
The PRO-2006 includes a SOUND SQUELCH, resembling the VSC
circuit on the ICOM R-7000, which may be used during scan or
search operations. With the the sound squelch enabled, sig-
nified by a red lamp above the pushbutton, the scanner will
skip over unmodulated signals. This is handy for skipping
over "birdies", link signals with a constant carrier, or
baby monitors when baby is asleep.
The manual warns that the sound squelch may be fooled by
signals with low modulation, and skip over them. The PRO-
2006 SOUND SQUELCH tries to detect the presence or absence
of modulation (not human speech), so unfortunately, it
thinks that noisy dead carriers, digital data signals, and
paging tones are worth monitoring and will stop the scanner
to listen to them.
A tape recorder can be connected to the TAPE phono jack on
the rear panel, which provides 600 mV of audio at a 10,000
ohm impedance. An audio filtering circuit rolls off the
high frequency components before they reach the TAPE jack,
which makes it impossible to use it for picking off FM sub-
carrier signals. In addition to a rear mounted external
speaker jack, there is a miniature headphone jack on the
front of the scanner.
The PRO-2006 lacks a COR (carrier operated relay) output,
like ICOM R7000 and older Bearcat 300 have, which would be
useful for actuating a tape recorder.
To evaluate sensitivity, the PRO-2006 was compared with it's
grandfather, the PRO-2004. Since a signal generator was not
used, quantitative measurements could not be made. Instead,
an Antenna Specialists AV-801 antenna was switched between
radios, signals from stations were compared by ear, and the
Simply put, the PRO-2006 proved more sensitive than the
PRO-2004 on all bands tested, and much more sensitive in the
850 MHz range. The earlier PRO-2005 was also more sensitive
then the PRO-2004, but both the PRO-2005 the PRO-2006 let
800 MHz trunked systems and cellular telephone conversations
bleed through while searching the 118 - 132 MHz commercial
aircraft band. The 800 MHz interference was heard on the
2005 and PRO-2006, not the 2004.
Although the PRO-2004, PRO-2005, and PRO-2006 can suffer the
effects of intermodulation, they are much more immune than
the overly sensitive, image laden Bearcat 800XLT. Intermo-
dulation from paging appeared on several frequencies above
1000 MHz, in a region not many people monitor. Oddly, audio
from television channel 50 was heard on 1251.625 MHz. The
PRO-2006 has a 10 dB attenuator, operable by a slide switch
on the rear. The attenuator helps eliminate intermod, but
few people would want the attenuator enabled while scanning
or searching as it degrades both wanted and unwanted sig-
nals. A programmable attenuator feature, selectable for
each channel, would have been a better idea.
The up conversion design of both the ICOM R-7000 and Radio
Shack PRO-2006 allows use of a very high IF (intermediate
frequency), which helps avoid image problems.
The audio output quality is good, although the top mounted
speaker directs the sound at the ceiling, but adding an
optional external speaker allows the sound to be directed at
the user's head.
Unfortunately, the audio level of AM signals is somewhat
below that of NBFM signals, requiring a slightly different
setting of the volume control, although this has improved
over the PRO-2005. When scanning both AM and NBFM modes,
one has to find a compromise position of the volume control.
The PRO-2006 squelch control has a small amount of hys-
teresis, an improvement over its GRE ancestors. Too much
hysteresis is like having too much play in a car's steering
wheel, or backlash in a gear set. This hysteresis forces
one to keep the squelch at a tighter setting, missing weaker
signals when scanning or searching.
Mechanical and Electrical Construction
The newest scanners use tiny surface mount components, which
permits manufacturers to cram more circuitry into smaller
cabinets. This technology makes home repair and circuit
modification almost impossible. The "lick and stick" parts
are so small it's are difficult to tell a surface mount
resistor from a capacitor, and components are rarely marked
with their values.
The PRO-2006 is smaller and lighter than the 2004. It is
enclosed in a gray plastic cabinet, with a plastic front
panel. If one is going to pay $400, one deserves to own
some metal, but several stages are internally shielded in
their own metal compartments. The entirely plastic cabinet
of the older PRO2003 allowed wideband noise to radiate out
of the scanner and into nearby shortwave receivers.
The PRO-2006 vertical front panel is an advancement over the
sloping panel of the 2004. You can stack the scanner on top
of other equipment and see the controls without standing up.
If sitting directly on a table, two hinged plastic feet,
padded with rubber bumpers, can fold out from under the
front of the radio to tilt it at a good viewing angle.
There is a single BNC antenna connector on the rear of the
PRO-2006, and the radio is supplied with telescoping antenna
which screws in through a hole in the top of the cabinet.
Internal construction is excellent, and the internal shield-
ing is commendable. Interstage shielding is very important
in a wide band receiver, to prevent it from "hearing
itself", an undesirable phenomena which results in birdies.
The PRO-2006 owner's manual lists dozens of birdie frequen-
cies. The shielding is much better in the PRO-2006 than in
the 800XLT, which uses no shielding around the 800 MHz con-
verter stage, and probably accounts for some of the birdies
in the Bearcat.
Frequencies and other indicators are displayed on a backlit
LCD (liquid crystal display) panel, and the level of back-
lighting can be dimmed by a pushbutton switch. As with the
PRO-2005, the poor contrast on the small LCD panel makes it
difficult to read a frequency more than just a few feet
away, and is nowhere near as good as the greenish blue
fluorescent display in the old Bearcat 300.
However, physically challenged and vision impaired scanner
buffs will appreciate the conventional raised rubber key-
board in the PRO-2006, Only moderate pressure is required
for actuation, and key depressions are confirmed by a mild
"beep" audio tone.
The PRO-2006 is the right size to fit under the dashboard of
intermediate sized cars, but there are few concessions to
those wanting to use this scanner in a vehicle. Perhaps
Radio Shack has been influenced by repressive laws restrict-
ing mobile scanners in a minority of states, like New Jer-
Although it can be operated on 12 VDC, neither a mobile
power cord nor mounting bracket are provided. These items
were included with earlier, pre-PRO-2004 Radio Shack models.
The AC power cord is not detachable, and would have to be
bundled up to keep it out of the way in a mobile installa-
The user manual is much better than the fold out sheet fur-
nished with Uniden scanner.
A single page frequency allocations chart is included, but
is very general. Trunked radio systems are mentioned, but
only briefly. Most people buying PRO-2006s probably have
other scanners and so will be somewhat familiar with scan-
The up conversion design of the Radio Shack PRO-2004/5/6
allows use of a very high IF (intermediate frequency), which
all but eliminates image problems. Ironically, the PRO-2006
owner's manual contains a section on images. This section
appears in the manuals for most other Radio Shack models,
and was thoughtlessly included in the PRO-2006 manual. It
babbles on about images being 21.4 MHz away from the real
frequency -- true for simpler models, but not so for the
There is no schematic. Thankfully, detailed service manuals
for Radio Shack scanners are usually available for $12.00 or
The PRO-2006 is warranted for 1 year, which is reassuring.
So with all these neat features, what's missing from the
PRO-2006? It would have been better to have more channel
banks with fewer channels in each bank, say 20 banks of 20
channels. A "search and store" mode, like that on the ICOM
R7000 and older Bearcat 250 would have been nice, and such a
circuit is being marketed by Key Research. A lighted key-
board and a signal strength meter would also be welcome, as
would a mobile mounting bracket and SCA output jack.
A frequency query facility, as found in the Uniden 200XLT,
would have been very useful to finding in what memory chan-
nel a given frequency is stored.3 Mega-channel scanners
really need this feature and it would have been trivial to
implement in the PRO-2006 firmware.
Summary - It's Tops
If all one wants is a scanner to monitor local police and
fire, there are certainly cheaper and simpler models than
the PRO-2006. This scanner is the best base/mobile scanner
available at time of writing. AOR's AR-2515 has more chan-
nels, but its buggy firmware and tendency to skip active
channels prevent it from taking top honors. At about $400,
the PRO-2006 scans much better than the ICOM R7000, a great
VHF/UHF communications receiver, priced at over $1000.
The PRO-2006 has the right features and performance, espe-
cially for scanning the wide 225-400 MHz military aircraft
band and the newer federal law enforcement radio systems
with their dozens of channels.
1. "Product Review: The Radio Shack PRO-2004 Programmable
Scanner," by Bob Parnass AJ9S, in The Radio Enthusiast,
February 1987, and Monitoring Times, March 1987.
2. "Product Review: The Radio Shack PRO-2005 Programmable
Scanner," by Bob Parnass AJ9S, in The Radio Enthusiast,
June 1989, and RCMA Journal, August 1989.
3. "Uniden/Bearcat 200XLT Scanner Review," by Bob Parnass,
AJ9S. The Radio Enthusiast, August 1988.
Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihlpy!parnass (708)979-5414