100-channel scanner
for home or mobile use
Last June, we reviewed the AR900, a
100-channel handheld scanner manufactured
by AOR in Japan. Now AOR has produced a
mobile version, the AR950, which covers the
same bands.
By GARRY CRATT
It is pleasing to see that after our
review of the AR900, AOR has
taken some of our comments to
heart and made several important
improvements to the design. First,
the AR950 receiver produces significantly more audio which is a
necessity for mobile applications.
In addition, there is provision for an
external speaker to be used, further enhancing mobile operation.
Other improvements have been
made to the instruction manual
(which is now easier to read) and to
the receiver squelch action, which
8
SILICON CHIP
suffered from "popping" in the first
AR900 sample submitted for review.
Basic functions
The basic functions of the AR950
are the same as for the AR900
handheld unit. There are 100 channels available for user selected frequencies and these are grouped in 5
banks (each of 20 channels). Each
bank is labelled A to E. Banks can
be added or deleted from the scan
list by pressing the relevant bank
key.
These keys operate as a toggle.
When the band has been selected
for inclusion in the scan list, the
relevant letter is displayed in the
LCD panel. When the bank has
been deleted, the letter disappears
from the display. Frequencies to be
scanned can be directly entered into memory while frequency bands
are being searched. This is quite a
useful feature because it allows a
particular band of frequencies to
be searched and when an interesting signal is found, it can be
located in any of the 100 memory
channels.
The advantage of having 5 banks
is that frequencies of similar interest can all be stored in the same
bank. For instance, all aviation frequencies can be stored in one bank
while mar ine frequencies can be
stored in another. It is then quite
easy to scan 20 frequencies
relating to the same service. In ad-
dition to the aviation and VHF
marine bands, other bands of interest include the VHF or UHF
amateur band, the UHF commercial
band, the UHF CB band, and the
cellular telephone band.
In addition, the AR950 has a
"priority" function which allows a
user programmable priority frequency to be toggled while scanning
a bank of frequencies. It also has a
"lockout" function which allows
unwanted channels to be bypassed
during scanning, and a "hold" function which disables either the scan
or search functions once a transmission has opened the receiver
squelch.
One of the more important and
often overlooked features of such a
scanner are the scan and search increments. The AR950 has increments of 5kHz, lOkHz and 25kHz
on VHF high and low band; 12.5kHz
and 25kHz on the airband, UHF
bands, and trunked 800-900MHz
bands; and 30kHz on the cellular
telephone bands. This should cover
all frequency allocations on all
bands!
Another plus for this particular
scanner is the use of EEPROM (Electronically Erasable Programmable
Read Only Memory) technology
which means that there is no need
for nicad batteries to back up the
frequencies programmed into
memories. With EEPROM technology, all data programmed into
memory is stored until it is updated
or deliberately deleted by the user.
Even if the power source is removed, the frequencies in memory will
be retained.
Antennas
The AR950 is supplied with two
antennas, one of which is a
dedicated 800-900MHz ¼-wavelength whip for improved reception
of the trunked radio and cellular
bands. These bands are becoming
increasingly popular with scanner
enthusiasts and radio technicians
alike. The other antenna is a
telescopic whip which is designed
to cover the VHF bands.
Most fixed point or "home" installations will, of course, use an
external antenna such as a discone.
Because of this, the AR950 has an
inbuilt switchable 20dB attenuator
for use when strong adjacent channel signals are present.
During testing of our sample, we
experienced interference of this
type from four Sydney television
transmitters which are located
within 1km of our test laboratory.
Switching in the attenuator reduced this interference to a level which
allowed us to set the squelch so that
all desired channels were received
without problems.
Protect Your
Electronic
Equipment
& Valuable Data Files
from a
Power requirements
The AR950 operates from 12V
DC and is supplied with a polarised
power lead with inline fuse. Also,
the unit has an inbuilt series diode
to prevent possible damage from
reverse polarity of the power
supply.
One criticism we do have of the
unit is that, when placed on a flat
surface (such as a desk) and when
viewed from above, the LCD is a little difficult to read. If the unit is
tilted upwards by raising the front
edge by 25mm or so, the problem
disappears. A simple wire stand
would have cured this problem but
this seems to have been overlooked
by the manufacturer.
Despite this shortcoming, the
AR950 represents good value for
money at the recommended retail
price of $399, especially when the
country of origin (Japan) is taken
into account. The unit is distributed by Access Communications, 33
Alleyne St, Chatswood, NSW 2067.
Phone(02)417 5311 for the name of
your nearest dealer.
~
With
COMPUTER
PROTECTOR
A definite must for all
electronic office equipment
Available in the folloWing Current Ratings:
I Amp, 3 Amp, 6 Amp, & I O Amps
..------Cl.l'l.l:IJJ ■
~
~5!Lng~se
I
SYSTEMS
Wanted: Your Circuit Ideas
Have you got a good circuit idea languishing in the old brain cells? If
so, why not send it to us for publication in Circuit Notebook?
We'll pay up to $70 for a really good circuit, depending on how much
work we have to do to knock it into shape. So transfer your idea to
paper, write a brief circuit description and send it to SILICON CHIP, PO
Box 139, Collaroy Beach, NSW 2097.
WESTINGHOUSE BRAKE & SIGNAL
COMPANY (AUSTRALIA) LIMITED
SIGNAL DIVISION
80-86 Douglas Pde, Williamstown. Victoria.
(PO Box 267, Williamstown. Victoria 3016)
Phone (03) 397 1033. Fax (03) 397 1861
Telex: 37 477 Wessys
Vic (03) 397 1033. NSW (02)5451322, Old (07) 275 3188
SA (08) 212 3161 , WA (09) 446 8844
COM/1
JULY 1990
9
