QRZ! Ham Radio 8/QRZ Ham Radio Callsign Database - Volume 8.iso/mac/files/infodata/dj_x1.txt

Text File | 1996-06-25 | 20KB | 356 lines

Review: Alinco DJ-X1 Scanner

Copyright (C) 1993 by Michael Schuster         Last revision: 14 Sep 93
                      ([e-mail])

INTRODUCTION

Back when the ICOM R-1 wideband pocket scanner had just been released
(except in North America) there was talk that another manufacturer of
amateur radio equipment, Alinco, was readying a similar model for sale.
That scanner, based upon the design of the DJ-F1T 2-meter handheld, came to
be known as the DJ-X1. Sized just slightly larger than the ICOM R1 in every
dimension, and having similar capabilities, it attracted my interest after
years of putting up with the R1's deficiencies:

     -    poor filtering
     -    lack of front-end AGC, causing severe overload problems
     -    images and poor ultimate rejection due to mixing of spurs from
          the noisy synthesizer (fixed by the Raycom filter upgrade)
     -    poor battery life using the internal 300 mAH battery pack
     -    poor performance on HF

The DJ-X1 has not been marketed by Alinco USA. Given the present regulatory
climate in this country, it is unlikely that such a continuous-coverage
receiver would ever be sold here. The only way to get one is to import it
from another country (Japan or UK). After selling my R1 I ordered a DJ-X1,
based upon a favorable review in ShortWave Magazine (UK) and positive
comments from several DJ-X1 owners on the Usenet. Since most North American
scanner enthusiasts are unfamiliar with this model, I was asked to write
this review to fill that knowledge gap. The DJ-X1 is a very strange bird,
as the following description will show.


PRICE

Since the DJ-X1 is not sold in the US, there is no reference point for
selling price. At the time of this writing, British dealers usually charge
between 280 and 330 pounds sterling ($420 - $495) which, not surprisingly,
is basically the same price as the ICOM IC-R1.


FIRST, AN APOLOGY

This review is going to be sketchy in some areas (specifications, battery
life, and actual measurements of sensitivity, selectivity, etc) as it is
based upon only a short period of use. I will be as complete as I can in my
assessment of this device without venturing into the area of speculation.


SPECIFICATIONS

Frequency coverage: 2-905 MHz guaranteed (tunes 100 KHz - 1300 MHz)
Modulation modes: AM/FM narrow/FM wide
Channel steps: 5, 9, 10, 12.5, 20, 25, 30, 50, and 100 KHz
Current draw: MAX: 300 mA    BATT SAVER: 24 mA
Receiving system:  AM/FMn: triple conversion  FMw: double conversion


EXTERNAL APPEARANCE AND CONTROLS

Just as the ICOM R-1 resembles the "SAT" series of handheld ham rigs, so
the Alinco DJ-X1 resembles the DJ-F1T and DJ-F4. While tiny, it has the
solid feel that ham equipment has, and which [sadly] most consumer scanners
lack. The case is heavy-gauge plastic and metal, the knobs feel sturdy, and
the keypad legends are printed on the case where they will not wear off
from friction. On top there is a standard BNC antenna connector, ganged
volume/squelch controls, and a click-stop VFO knob. On the right side are
phones/line-out and DC-in connectors; each with a permanently attached
protective rubber flap. The power connector is a standard mini coax and
nominal 9VDC, center positive. On the left is a large rubber pad having
three indented buttons. These are "additional function" keys which are used
in conjunction with the keypad. These F-keys are located exactly where the
push-to-talk switch would be on a ham rig, giving the visual impression
that this is, in fact, an HT rather than a scanner. I suppose that in
certain situations this could be a plus.

The width and height are just a touch larger than the ICOM R-1. Rather than
having an internal battery pack, the DJ-X1 has a slide-on pack which clips
to the back, and has the same height and width as the scanner itself. The
battery is attached to the back of the scanner via a spring-loaded metal
catch. This can be locked to prevent accidental release. The supplied 700
mAH pack is hefty, and makes the DJ-X1 a full third fatter than the R-1.
The DJ-X1 used to be shipped with a clip-on battery case which came empty
(you filled it with nicads yourself). Perhaps in order to improve sales,
current models ship with a sealed battery pack that is not user-modifiable.
The belt clip screws onto the battery pack, since when attached it actually
forms the rear surface of the scanner. There is also a loop for a
(supplied) carry strap as with the R-1. Note that while there is a DC-in
socket on the scanner itself, power connected there will NOT charge the
attached battery. You have to use the external charging stand to do that.


ACCESSORIES

Other accessories supplied are a charging stand (with integral wall
transformer according to country of sale), belt clip, carry strap, and two
rubberized antennas. The antenna described as "low band" seems to be peaked
for low-band VHF, high-band VHF, and to some extent 220. The "high band"
duckie performs best on UHF and 800. There is considerable overlap,
however, and Alinco seems to have recognized that no single rubberized
antenna can hope to adequately cover the wide receive range of this radio.
Neither antenna is adequate for shortwave. During my testing of this model
I almost exclusively used the GRE all-band rubber antenna that I bought for
use with the Yupiteru MVT-7100. On the bands that each Alinco antenna seems
to be peaked for, they perform similarly to, or very slightly better than,
the GRE antenna. Alinco sells a $20 vinyl case for the DJ-F1T which also
fits the DJ-X1. It has clear vinyl overlays for the display and keypad, and
cutouts for other controls and attachments. Its method of closure, which
must be able to accommodate the different size battery packs that might be
attached, is unique: the back consists of two mating surfaces of
Velcro-style material that can maintain whatever size that might be
necessary to make the case fit snugly with the scanner as currently
configured. It works. Also, the fill-your-own battery case that used to be
standard equipment with this scanner, is still available as an accessory
for the DJ-F1T and DJ-F4 scanners from Alinco USA.



DISPLAY

The tiny speaker is front-mounted near the top of the scanner. The speaker
grille is flanked on either side by a column of push buttons (2 on the left
side and 4 on the right). Below the speaker is the tiny LCD display. The
contents of the LCD panel gives the first hint at how odd this scanner
really is. First, the numerals are tiny, and of different sizes. The
hundreds digit is smaller than the other two, and there is no direct
readout of increments below 5 KHz. Instead, truly minuscule LCD segments
bearing the legends "50", "25", and "75" are activated when needed. So
476.3875 would be displayed as little 4, plus large 76.38, followed by an
activated "75" bar. To the left of the hundreds digit are two smaller
digits which indicate the memory channel number. Frequencies about 1000 MHZ
are indicated by the illumination of an "over 1000" bar, not by a "1" digit
on the LCD.

There are indicators for numerous scanner modes and functions, which are
equally tiny as well as cryptic. For instance, narrow FM mode is indicated
by a symbol which looks like a boat anchor. AM modulation is indicated by
the letter "A", and wide FM mode by the illumination of both the boat
anchor and "A" symbols. The scan/search speed is indicated by the number of
segments in a tiny pie chart. One segment means 10 cps, two means 15, and
three mean 20. A small "V" or "M" (actually \/ and /\/\) indicates whether
one is in VFO or memory mode. Tiny additional LCD segments (bars,
triangles, numerals) are added to indicate which memory bank is active.
Also, there are one or two-letter indicators for battery saver and duty
cycle, and for other functions that are not worth cataloging here.
Curiously, although there is a defeatable "beep" which sounds when you
press any of the buttons, its on/off state is not indicated anywhere on the
display. The fact that the scanner is scanning or searching is indicated
only by the fact that the decimal point of the frequency display is
blinking. There is also a horizontal signal strength meter like that on the
Yupiteru or ICOM handhelds. I did not evaluate its accuracy or linearity.

The LCD display is sidelit, and like the Yupiteru MVT-7100 the main keypad
below it is translucent so that it is illuminated when the dial light is
active. The dial light has two modes: a standard "push and it stays on for
a few seconds" mode, and a novel "automatic" mode. In the latter situation
the dial light goes on whenever you manipulate the controls. This is a
great idea, and I wish the other manufacturers would do something like
this!


KEYPAD

The main keypad has tiny buttons but they are well-spaced and not recessed
as on the ICOM, so that they are easy to find and press without error. The
"ENTER" button is not in a logical place, and its label is not highlighted
in any way as to make it easy to find. Most of the buttons on the keypad,
and on the columns of buttons aside the speaker, have dual functions. The
main function is printed in white above the button, and the secondary
function printed below in blue. To activate the second function you
simultaneously depress the first "function" key on the left side of the
scanner. There is no indication on the LCD that you have activated any of
the "F" keys. Each of the three "F" keys may be used in conjunction with
the VFO knob to rapidly increment one of the three MHz digits. But there is
no indication on the LCD as to which one you are about to change, until you
actually see it happen while turning the VFO knob.


OPERATIONAL FEATURES

The scanner has the standard set of functions one would expect from this
type of product: scanning stored memory channels, limit search, priority
channel, manual entry, and moving data between the VFO and memory channels.
There are 100 memories which are arranged into three groups: two "scanning
memory" banks of 40 channels each, and one "search storage" bank. The two
40-channel scan banks cannot be linked. Any number of the 40 channels in
each (referred to as the main and sub bank) may be individually locked out.
The other 20 channels are used in an unusual way. The first 10 (L0, U0, L1,
U1, etc) store the limits and modulation of the five available search
banks. They do not store the channel increment you have selected; more on
that later. The other 10 channels are filled automatically during a
frequency search. This function is essentially useless, as the DJ-X1 lacks
the "zero-matic" or "center-track" tuning found on Uniden or GRE scanners.
So search may stop well short of the actual frequency of a signal found
during search, and each break of the squelch fills another of the 10
scratchpad memories. When these memories fill, they are re-written, and
there is no provision to prevent duplication of entries. There is no
provision for locking out individual frequencies (such as those where
birdies or uninteresting signals exist) from being received during a
frequency search.

The manual does not state whether memory channels are volatile (i.e. if
they will eventually get cleared some time after the batteries die or are
disconnected). In my use of the scanner it seems that the memory channels,
operational settings, and current mode are probably stored in an EEPROM and
therefore do not disappear when the batteries run down. This is a plus over
the IC-R1 which uses a secondary lithium cell to back up the memories for
a few days after the main battery is exhausted.

Entering frequencies on the DJ-X1 is done in a most unusual way. It is not
difficult, but it takes some getting used to. Basically you cannot directly
key any value smaller than 10 KHz. You must enter a frequency nearby, and
then use the VFO knob to increment to the actual frequency. Best shown by
example: to enter 151.505 MHz, for instance, you would select a channel
increment of 5 KHz (see below) and then key in the following:

     1  5  1  .  5  ENTER

and the display would indicate 151.50; from there you would click the VFO
knob upwards one notch so that the little "50" bar is illuminated. Voila
... 151.505 MHz.


The DJ-X1 has a full range of channel increments from 5 to 100 KHz.
Selection of increment is pretty straightforward: press the "step" button
and the currently active increment is displayed. Click the VFO knob up or
down until the one you want is displayed, and then press the memory/VFO
button to go back info VFO mode. The LCD then displays the tuned frequency
(which may have changed in order to conform to the new step you have
selected). This much like the MVT-7100.

Initially it seemed that manual selection of step (increment) size is
ignored when the scanner searches between frequency limits. The scanner
insisted upon choosing a step size based upon defaults that are stored in
ROM, and which almost always seem to be 5 KHz. So if you choose to search
for police signals between 470.6375 and 471.6625 MHz, for example, you will
be able to enter these frequencies accurately into an Ln/Un memory pair.
But when you activate the limit search (called programmed scan) between
those two frequencies, the scanner searches in 5 KHz increments, not 12.5
as would be assumed given these frequency limits. As a result, it searches
in between the actual assigned channels.

It turns out there is a way around this. Buried in the manual is a small
note that FUNCTION-0 on the keypad toggles the state of the auto mode (and
increment) select function. Not only is the zero key unlabelled as to the
presence of this additional function, but the LCD display does not give any
indication as to the status of autoselect mode. But using FUNCT-0 to turn
off autoselect (the default ... you guessed it ... is "on") allows you to
limit search using the channel spacing you have first selected using the
keypad and VFO knob. You must also change the modulation mode if necessary.
Granted you must select the increment manually every time you use a
different pair of search limits, but the actual number of keystrokes
compared to, say, the AR-1000, is still much less and the steps are easy to
master.

There are two ways of doing a frequency search without upper and lower
limits (i.e. pick a frequency, modulation, step size, and direction and
just keep going). In these functions the scanner will use the step size you
have chosen regardless of the status of the automode function.


SHORTWAVE PERFORMANCE

First, let me dispense with the issue of medium and shortwave reception. No
"continuous coverage" scanner will perform like a dedicated shortwave radio
costing even half its price. The DJ-X1 is no exception. However, it does
have adequate sensitivity to receive more powerful international shortwave
broadcasters when attached to a reasonable telescopic whip antenna. It will
even receive powerhouse signals using the GRE rubber duckie, which puts its
sensitivity in the class between the AOR AR-1000 and Yupiteru MVT-7100.
Filtering in AM mode is very broad, and many signals suffer from gross
bleed-over of signals in adjacent channels. The product specifications are
guaranteed only down to 2 MHz, and my limited testing bore that out. There
are two reasons for that conclusion: first, sensitivity drops off
dramatically below 5 MHz or so. Second, the lower you go, the more the set
is plagued by powerful internally-generated birdies. So, the DJ-X1 will be
useful for casual shortwave listening; nothing more.


"SCANNER BAND" PERFORMANCE

Sensitivity/selectivity on the other bands is adequate; much better than
the ICOM R-1 but not in the same class as the GRE PRO-43 or Yupiteru
MVT-7100. In Manhattan I found that, like many scanners, the UHF band was
filled with intermod from paging transmitters. Again, this was somewhat
better than the R1, but using the Alinco can be challenging under these
conditions. At home in tue suburbs, it was much better behaved, but I did
find snippets of signals where they didn't belong in various bands and out-
of-band segments.

As indicated before, the DJ-X1 will scan/search at 10, 15, or 20
increments/second. The manual warns that weak signals can be missed at
either of the two faster speeds. I found this to be true, but noted also
that it seemed to occasionally miss strong signals as well. This, however,
may be related to the next problem I had with the scanner - "stuttering"
while scanning memory channels.

After programming about 20 local frequencies into the main scan bank, I put
it into memory scan mode and listened. The scanner seemed to be
"stuttering" - that is, it kept getting tripped up on several of the
programmed frequencies even when no transmission was present on those
channels (as verified by an MVT-7100 programmed with the same frequencies).
Since there is an obligatory 2-second delay after squelch is broken, this
frequent interruption greatly reduces the effective scan speed. Raising the
squelch threshold made it stutter less, so I began to think the Alinco was
stopping on false signals like the R1. But the phenomenon was quite
different, and not consistent. Stepping manually through the memory
channels I found that the squelch would sometimes open for a fraction of a
second when moving from a channel having a frequency in the VHF-hi range,
to a channel having a frequency in another band. For instance, if CH#0 had
151.925 and CH#1 had 450.800, moving from CH#0 to CH#1 would sometimes
cause a noise burst, while moving from CH#1 to CH#0 would not.

I thought at first that the VFO was generating noise bursts when stepping
through adjacent channels required it to make big jumps in tuned frequency.
But the intermittent nature of this phenomenon led me to eventually abandon
that theory. Listening to the memory channels having VHF-hi frequencies
with the squelch open, I occasionally heard faint interference in the
background, sounding something like the video carrier of broadcast TV. My
working theory is that this subtle intermod interference is intermittently
breaking squelch on VHF-hi, and interrupting smooth memory search in the
process.


AUDIO

The R1 showed that passable audio was possible even when using a tiny
speaker. Audio on the DJ-X1 is not as good as on the ICOM. While the
speaker is the same size, it provides sound which is more restricted in
frequency range and somewhat more distorted. It is equally poor through
headphones connected to the jack on the side of the radio. This is really
not too objectionable when listening to the bark of a police dispatcher,
for instance, but further limits the useability of the scanner for
broadcast listening (shortwave or local programming).


SUMMING UP

I began by introducing the Alinco DJ-X1 as an "odd bird". I hope that my
rather verbose description of its configuration and operational
characteristics have made that statement clearer. The search for the
perfect pocket scanner, sadly, still continues. Any wideband scanner,
particularly one with continuous coverage, is an expression of the art of
compromise. Any ultraminiature scanner is also built with design
compromises. So ultraminiature wideband continuous-coverage scanners like
the Alinco DJ-X1 and ICOM IC-R1 are doubly compromised in their design. I
think that overall the DJ-X1 is a more useful receiver than the IC-R1,
especially since filter upgrades for the R1 are no longer available.
Certain aspects of its operation (stuttering during scanning past some
frequencies, and arcane displays and operational logic, for instance)
detract from its better RF performance. If size is your overriding
consideration, I suggest that you compare both receivers carefully before
deciding.