Special gratitude to Fatos
Adami (Philadelphia, USA) for preparation
of the english version.
The Model DE 1103 is a newcomer from DEGEN.
When it appeared in the market, the radio practically attracted the
attention of the radio listening enthusiasts immediately. It looks beautiful
and well made, and the list of available features for the price tag
makes it even more attractive, if not for purchasing, to just hold it
in your hands.
After targeted searches in the stores of Moscow, I got in my hands
the shiny box. “The dress sells” and the Chinese understand this rule.
The item attracts the attention with a colorful box with the picture
of the receiver and the list of its features written on it.
DEGEN DE 1103 is quite compact and light, with the
whip antenna and the strap to hold it in your hands. According to all
criteria, this is a travel radio. It is not cheap (in Moscow DE
1103 is sold for nearly $100) but is not expensive either like
the other known brands. Therefore, in the review below I will try to
compare the newcomer with the known representatives of this category
of radio receivers: Grundig Yacht Boy 400 and Sony
Opening the box, you see the receiver itself, the power supply/charger,
earphones, the wire antenna for shortwave receiving, four NiMH batteries
and the original velvet case. That’s not bad for a relatively inexpensive
The external antenna is a wire with a clip on one end and a 3.5mm jack
on the other one. This is inconvenient for frequent use (unlike the
reel antennas for 7600GR and YB400), but nevertheless it is simple and
does the job well.
The earphones are simple and work right. A careful look of accessories
makes apparent the similarity of the supplied earphones with the SENNHEIZER
MX200/MX300, which are not bad for their class. Apparently, DEGEN has
trusted suppliers, and all the accessories flaunt mark “DEGEN”.
Four NiMH 1300mAh reachargeable batteries are included in the package.
The capability to charge the batteries inside the receiver is an indisputable
advantage of the DE1103. A power adapter is included in the set for
this purpose. When you listen, you might not think that the time to
change batteries is approaching. But battery wise, the DE1103 cannot
be considered as economic. We’ll talk later about its power consumption.
A cute item among the accessories is the velvet bag with the tightening
strap. You can put the radio and other stuff in it. Of course, the leather
imitation case of YB400 is more practical, but to ask more for this
price would be naive.
Let’s go back to the main character of the story and take a closer
and multilateral look to the newcomer.
The model comes in two color variations – silver and purple-violet, according
to the color of the front panel. I got myself the second variety.
The outside look and main functions
The back part of the main body is the same for both models.
The high quality of the elements of the main body of the receiver and
the materials from which the DE1103 is made are noticeable. The design
is sturdy and well made. Nothing scratches your hands (there are no
burrs), the tolerances of the gaps between the parts of the receiver
are kept to a minimum. All the small parts are varnished and polished:
buttons with inscriptions, moving parts of the switches, and the tuning
knob are made flawlessly.
Yes, China today is not what it was earlier.
A stylish solution of the outside look for DE1103 is the frame around
the rectangular buttons, the frame of the main display, and the inscription
“DEGEN” itself; all of which are made from machined aluminum with visible
inclined lines from the milling machine. True metal, not plastic!
After admiring the radio by holding it in hand, let’s go into more
Dual conversion of frequency.
FM: 76.0-108.0 Mhz.
AM/SW/LW 100-29999 Khz (1Khz step, two band pass switch narrow /wide).
Knob of smooth tuning /automatic frequency scan/memory scans. /direct
entry of the frequency.
Sleep switch / timer for turning off.
Outside charger (power supply).
SSB receiving with fine tuning.
Oversized LCD display with digital indicators and imitation of analog
Indicator of signal strength.
Indicator of battery charging.
DX/LOCAL switch for shortwave reception.
Two position tone switch: MUSIC AND NEWS.
Low battery indicator.
Charger/power supply (including 4 Ni-MH batteries).
Orange backlight of the display and push buttons.
Line out jack.
Outside antenna jack.
Powered by four AA batteries.
Accesories: earphones, wire antena, power supply for 220V
Dimensions: 165 x 105 x 29 mm
*this is the translation of the advertising on the box in the absence
of other technical data except for the Chinese manual.
DE1103 differs from the other known digital receivers (most of which
are made in China too) because of some original features.
First, there is the display. This is the central element of DE1103
that attracts the attention of the amateur. Its area, which takes almost
half of the front panel, is original. The display of the DE1103 looks
like it links two epochs of the development of radio receivers. Instead
of the pure digital display, the designers put an imitation of an analog
one with a digital horizontal bar that moves up and down with the rotation
of the tuning knob. In the photographs this display looks very much
similar to the mechanical ones that have wave bands and the numbers
indicating the frequencies. The design makes a pleasant impression to
people who remember old radios.
Secondly, the tuning knob. The PLL of DE1103 has a round knob. The
rotation of the knob is surprisingly easy and uniform. Most of the PLL
sinthesized shortwave receivers have up and down tuning knobs. Only
more expensive receivers have this kind of tuning device.
The back lit display is another feature. This is an additional “plus”
of the receiver. The display and the inscription of all the buttons(!)
glow in the dark with a mild amber like light. The way the back light
works is the following: it turns on automatically by pressing a button
or turning the tuning knob and stays on for a few seconds after the
button or knob is released.
Unfortuantely, the lack of photographic skills did not allow the author
to reproduce the beauty of using the DE1103 at night:
It is very convenient to use DE1103 in the dark! You can easily use
the radio even in the pitch dark, unlike the other models of receivers
that provide the back lighting for the display and the on/off button
only. The back light feature can be turned off with a switch on the
right side of the radio if saving the battery power is needed.
One of the advantages of the DE1103 is the possibility of receiving
single side band signals. Not all the small receivers have this feature,
but precisely the possibility of SSB reception is often an important
argument for the radio enthusiasts in deciding to buy a portable device
with “all in one” features.
The fine tuning knob, the main tuning knob, and the wide/narrow band-pass
switch are on the right side of the receiver.
On the right side are also the switch to turn on/off the back-light
and the line out jack. This last feature is a rarity for receivers of
this class (not to be confused with the earphone output jack). It can
be a useful feature in some situations.
The earphone jack, the jack for the outside wire antenna, and the one
for the power supply are located on the left side of the radio. Also,
here is the switch for the attenuator DX-LOCAL.
The volume adjustment for this receiver is electronic. To change the
volume a button needs to be pressed on the upper left side of the front
panel, and then with the tuning knob you can select the desired level
This is a little inconvenient and not straightforward, but with time
you get used to it.
It is unfortunate, that in the small body of DE1103 it could not be
found a place to put a conventional volume knob.
Many buttons of the receiver are multi functional and have at least
two functions. The independent study of the functions is made easier
by English inscriptions, but the descriptions of some features can be
found in the Chinese manual only. This means that they are accessible
only to the hieroglyphologists or to them who do inquisitive studies.
DE1103 has a buid in clock and two alarms. They all work with the 24
For each alarm you can set:
- The time the alarm goes off (the time the receiver is turned on during
- The memory number or the last channel it was on (the one in which
the receiver was before being turned off),
- The volume of the station in the time the alarm goes off,
- The time the sleep mode comes into effect (between 5 and 99 min.).
If the possibility to set two alarms is a normal feature, the lack
of a second time clock is unfortunate for DX amateurs who cannot immediately
see the UTC display.
Also a dream is the wish to have a calendar with changing date in the
big display of DE1103. These are small flaws that go in the favor of
When you put the batteries inside the DE1103 the clock is immediately
turned on. The clock does not have a second’s indicator like in the
Bad news is the impossibility of the DE1103 to keep the time during
the battery replacement. Although internally rechargeable batteries
are provided, they still might need to be changed. Sometimes the time
can be kept during the battery change, but in most of the cases the
time display takes the most abstract appearance during this procedure.
In this case the receiver cannot be turned on and the processor is blocked.
For similar situations a smart internal knob is provided in the front
panel of the DE1103. After the RESET procedure is performed, (by pressing
the internal button through the reset hole) the clocks are turned back
on and the receiver is ready to work.
Good news is that the internal memories remain intact during this procedure.
DE1103 is powered from four AA batteries. Those can either be the supplied
rechargeable NiMH or normal alkaline ones. In the last case the designer
has put a warning in the back panel about the danger of trying to charge
these kinds of batteries using the internal charger.
The measurement of the working current gave the following results:
In the AM band (LW, MW and SW bands) the current was about 75mA for
a low volume of the speaker. For the maximum volume, the current reached
about 130mA. A little less current is needed in the FM band, respectively
58 and 100 mA. Going in SSB mode added 11 mA more to the current. Also
the backlight takes an additional 20mA from the rechargeable batteries.
When the receiver is turned off, the current consuming is about 20 µA
for the standby mode and for the clocks.
DE1103 does not suffer of bad “appetite.” The presence of the rechargeable
batteries smoothes the “sin of gluttony”. A convenient new feature for
the DE1103 is the internal timer for battery charging.
In general, it is known how important it is to charge the batteries
right for an efficient use of their capacity and have them live long.
A basic and simple method is to charge the batteries with a constant
current for a given time. This time in hours is calculated as the ratio
of the battery’s capacity with the charging time multiplied by 1.4 to
1.5 (this is right for currents up to 0.25 of the batteries’ capacity).
Most of the slow chargers control the charging time and warn about
the necessity of turning off the device at the right time to prevent
the overcharge and damaging the batteries.
The DEGEN engineers supplied their receiver with an internal charger
and a timer for it.
At the beginning of each charging cycle, the user can select the time
in the limits of 1 to 23 hours. The measured charging current during
this procedure was about 85mÀ (100 mA in DEGEN’s manual).
It is unquestionable that this is more convenient than to do the math
yourself and remember when to turn off the charger.
The receiver DE1103 is turned ON/OFF by pressing the specific button
in the front panel. The same button activates the sleeping mode. To
set the “sleeping” feature (automatic turn off), turn on the receiver
and keeping the ON/OFF button pressed, rotate the tuning knob to select
the time in the 1 - 99 minute range then release it. The same time can
be set (when the receiver is still off) by selecting it by using the
0-9 numerical buttons and then pressing the ON/OFF button. The receiver
being on will automatically turn off after the preselected time runs
After the receiver is turned on, the clocks are substituted by the
digital frequency indicator. To see the time while the receiver is turned
on, the appropriate button (time button) has to be pressed. Unfortunately,
there is no possibility to see simultaneously both the time and the
tuning frequency (as in the case of YB400).
On the upper side of the display, above the columns of the graphic
scale, is placed the basic information: the signal strength indicator,
the icon of the battery charge, the tuning frequency, the level of the
speaker volume or the memory number and the “key like icon” for locking
of all of the receiver’s functions.
The PLL allows tuning by direct entry in the given frequency in the
100…29 999 Khz or 76…108 Mhz ranges. A row of numerical buttons is provided
below the display for this purpose. About the buttons, because of their
small size and relative hardness, pressing them precisely can be a complicated
business, even for people with not too thick fingers.
The tuning step, if you use the tuning knob, is 1 Khz in LW/MW/SW bands
and 25 Khz in FM-band.
Despite the discrete tuning, the station search with the knob reminds
you of the smooth tuning in the analog receivers. This is realized by
tuning without muting. It is this feeling of straightforward tuning,
of touching and listening with the DE1103 that makes it attractive,
in contrast with the up/down tuning of other receivers.
After a short use of the receiver it became evident the need for having
an additional tuning step of 9 Khz in LW/MW and 5 Khz in SW broadcast
bands. It is how it is done in the YB400 case. Because of the minimal
1 Khz tuning step during the search for broadcasting stations, you can
spend excessive time in the precise tuning of the radio-stations. This
The manual tuning of the DE1103 has a small flaw. This is a generation
of a small noise during the tuning like “blip-blip”. Although these
sounds can be heard only in the quiet parts of SW bands, its presence
kind of spoils the good feeling of the smooth tuning of DE1103. The
study of this phenomenon showed the reason why it happens (more details
in the technical part of this review).
Simultaneously with the tuning, the horizontal line of the analog scale
moves vertically on the main display stepping up and down and placing
itself in the right position of the vertical columns of different bands.
With time it became apparent the practical use of this “simulator” of
the tuning mechanism. The position of the tuning frequency in the broadcast
bands is well visible, and the small frame around the band number in
the upper part of the column indicates the band itself. Therefore, now
you have in front of you the standard map of the broadcast bands and
don’t need to rotate receiver (like in the case of YB400).
A little inconvenient is the cyclic tuning inside the same band. When
the upper or lower limit of the given band is reached by the rotation
of the tuning knob, the receiver automatically goes back at the opposite
end of the same band and the tuning starts over again within the same
one. This is convenient during the search for the stations within a
band, but makes more difficult the general surfing in the whole SW band
when you want to disregard the limits of the sub-bands. There is one
fix for this: – select a frequency using the direct entry feature let’s
say 1Khz up (or down) the limit of the given standard band and then
continue the manual tuning in the desired direction using the tuning
I liked the capability of the memory to stay tuned to the last station
visited in each band. If you leave the given band with any method (by
pressing the buttons “BAND-”, “BAND+” or with the direct entry of the
frequency), then if you turn back to the same band by pressing the buttons
“BAND-” or “BAND+” the receiver tunes itself in the frequency where
it was before and in the same mode AM or SSB. This is very convenient
if you have to go to one frequency and then turn back where you were
before without passing through the memory scan and/or the procedure
of another direct frequency entry.
There is an auto scanning function inside the same band. To do this
press and hold the corresponding up or down button (which is band+ or
band- button) for a second or so. The receiver will start a noiseless
search within the corresponding band with a 1 Khz step in LW/MW, 5 Khz
in SW and 25 Khz in FM-bands. When it finds a signal, the DE1103 stops
for three seconds turning on the sound. If you don’t press any button
during this time, the search continues. If you want to stop in the station
that you just found, press the band+ or band – buttons again.
The tuning speed during the search is about three steps a second, but
the search itself in LW/MW/SW does not work in an optimal way. The receiver
stops in the strong signals only, ignoring the weak and even medium
strength broadcast stations. In the same test for the “goody” YB400
practically nothing escapes its attention during the search. But the
high sensitivity of the search schematic has its downside, the sensitivity
to the noise is noticeable during the reception in urban areas. It practically
stops at every noise.
The signal strength indicator for the DE1103 is made in the form of
discrete “inclined plane”. It has four strength levels only, but with
increasing number of segments. The same feature is present in the case
of the S-meter of the YB400 too. The rise of the “inclined plan” is
two segments for each step of the signal strength increase, with the
exception of the last step in which the rise is three segments.
DE1103 does not have that big inertia of the strength level indicator
from which the YB400 suffers. The change of the levels here coincides
faster with the dynamic level of the reception signal. Unexpected was
the lack of the signal strength level indication during the reception
in the FM band. From the technical side this flaw is understood; the
schematic of the strength level usually is attached to the AGC (automatic
gain control) of the receiver, and this one is not used in the portable
receivers in this band (FM). Nevertheless, in the YB400 the simplified
strength indicator works in the FM band also.
As I progressed with the study of the receiver, it became clear that
the function of the battery charge control is not limited to the wave-like
movement of the respective “inclined plane” icon during the battery
charge when the receiver is off. If you press the button of volume adjustment,
during a few seconds when the volume indicator is on, the “inclined
plan” indicator in the display shows the remaining battery charge. The
battery strength indicator stays on a little more. This is more convenient
than simply the abrupt shut off of the receiver when the batteries reach
the exhaust point.
The receiver has 268 memories. They are more than enough for most users
and in any case more than the available memories in the similar competing
receivers. But the record capacity of memory sets forced the designers
of the DE1103 to use all the alphabet of two digit memory indicator.
Whoever is not familiar with the hexadecimal system will be surprised
during the memory scan with the tuning knob by appearance of the 10th
memory as “OA”, and the last one, the 268th as “FE”. This
mathematical trick may give a head ache to the active users of the memory
For those who feel better with the decimal system, there is a simpler
way around it. During the memory storage, you can simply select the
memory number by using the numerical buttons underneath the display.
In this way you can write in the memories (from 00 to 99) out of 268.
During the memory scan, the active memories will change increasingly
from 00 to 99. The rest of the memories do not show up, but they can
be activated by storing another station after selecting its number and
using the tuning knob only.
Besides the frequency, in the memory can be stored (and recalled) the
receiving mode in SW bands (ÀÌ or SSB). This convenience does not exist
in all models of receivers with SSB capability.
It is unfortunate that text messages cannot be stored in the memories.
Anyway, by the memory storage capability, the DE1103 stands out of the
top models of the portable SW receivers.
Despite the fair amount of information available in the display, there
is a feeling of a kind of “waste of space”. Probably, the major complaint
might be the use of about 80% of it for the digital simulation of the
analog graphic scale.
Not very convenient for use seem to be the switches of the band pass
and signal attenuator. The insufficient roughness of their surface combined
with some stiffness makes them kind of hard to switch up and down with
the fingers. We mentioned above the problem with the small numerical
buttons. For the rest of controls there is no complaint.
Related to the reception performance, the DEGEN DE1103 can be compared
with GRUNDIG YB400, taken as a standard. In the circles of amateurs,
the YB400 is praised for its excellent sensitivity and selectivity.
Most of the portable receivers of this class show in the best case similar
In the first test outside in the SW band using the whip antenna, the
newcomer won hands down by a clear margin. DE1103 received the signals
clearly and loudly enough, the same signals that in the YB400 were barely
distinguishable from the noise level. This performance was obvious in
the frequencies from 3 to 20 Mhz, and only in the frequencies above
25 Ìhz the signals were received with almost the same strength.
In both receivers the appropriate selection of IF filters helps select
the weak signals from the strong adjacent stations in the busy parts
of the SW bands. This is true even in the case of their presence 5Khz
away. But in the DE1103 the narrowing of the band-pass reception during
the switching in the narrow filter is much more obvious than in the
The sensitivity in the FM band is equally good. In most cases the programs
of the Moscow FM stations can be received without deploying the whip
antenna and without worsening the reception quality. The 77 mm speaker
doesn’t sound bad in the compact body of DE1103, but the sound in the
YB400 has more volume and depth because of its bigger dimensions.
The quality of the reception can be fully appreciated with good quality
headphones only. You should not forget to turn the tone switch in the
position “WIDE” or “MUSiC”. Changing position of the tone switch from
“MUSIC” to “NEWS” sensibly cuts the high sound frequencies, changing
also the signal in the line out jack.
The stereo decoder of the DE1103 has a high sensitivity, with the red
LED stereo indicator turned on even with a weak signal. But, like in
the majority of receivers, in the low signal strength conditions the
stereo reception is noisy. The choice of the 10.7 Mhz IF filters can
be considered appropriate; in the saturated Moscow’s FM band there was
no interference from adjacent broadcast stations.
The reception of the SSB signals in the DE1103 was a welcomed surprise.
As in the YB400 case, the tested receiver has a two band reception in
SSB. Here there is not a separate switching of the side bands; they
are received simultaneously. But unlike the same feature in YB400, the
fine tuning wheel in the DE1103 controls the tuning of the frequency
of the third (last) heterodyne. With some practice this allows the user
to tune the frequency of the supporting generator in one of the slopes
of characteristic filter, thus realizing a better reception separately
in LSB or USB.
The amateur and service stations are received with good selectivity.
In the presence of the high density of simultaneously working SSB transmitters,
“tails” from the neighbor stations appear; nevertheless, the width and
slope of the “narrow” filter is up to professional standards. But this
kind of reception condition is rare. The width of the band-pass for
the “narrow” filter in the DE1103 is optimal for its convenient use
either in ÀÌ or in SSB mode.
During testing in SSB mode for the DE1103, I found out one problem.
For a certain position of the hand in the body, like touching the right
back side of it and the plate of the front panel, the clarity of the
tone of the receiving signal worsened. It became wheezing and like rumbling.
I found the reason for this flaw, and I will describe its fix below
in the technical part of this review.
The lab measurement of the sensitivity of the DE1103 confirmed the
high results obtained during the “hearing” test. The findings are shown
Sensitivity (in µV) from the jack of the outside antenna
in different receiving frequencies. The ratio S/S+N (SINAD) is accepted
to be equal to 10 db.
| 16 MHz
| 13 MHz
The high sensitivity of the portable receivers usually comes together with mediocre performance in inter modulation and overload stability. This is a long time established technical fact. And preparing the newcomer to the test of “shock handling”, I was ready for the nth time to observe the classical picture of switching from the good reception with the whip antenna to the mess and inter modulation of different sounds from the superposing stations during the attachment of the outside antenna.
The attachment of the outside antenna to the respective jack of DE1103 reminded me of the interruption of a contact, or the attachment of an additional wire. The ethereal noise and the level of reception sharply increased, but the receiver worked reliably and received the signals the same as before, exactly where they should be. I took a look on the left side of the radio, and I was surprised even more. The attenuator was in the DX position! Switching the outside antenna quickly to the YB400 caused the expected overload, and I had to use the attenuator. I switched back the outside antenna to the DE1103 and the picture was totally reversed.
The scanner AR8200MK3, adjacent to the tested radio, during the attachment of the same antenna hissed, showing full reception strength. This is a normal reaction for a scanner. Despite the fact that its sensitivity in SW band is almost the same as the one reported with the above table for the Chinese radio, in the presence of the powerful signal AR8200MK3 is obviously a loser. The attempts to find and receive any normal signals with MK3 with the outside antenna were unsuccessful; you could listen only to the tips of the icebergs in the ocean of the broadcasting radio stations.
I turned on the HF transceiver with spectrum analyzer to evaluate the signal
in the moment of the experiment. I thought that the antenna had not
picked up enough of a signal, but I never thought that the Chinese receiver
would be so stable with the outsideantenna. And in my head a new thought
was coming: “Can it be true?”
So, we have a new champion! From my collection of receivers, only the heavy weight IC-756PROII still remained a worthy opponent for the DEGEN DE1103 in the powerful waves of the ethereal ocean. The GRUNDIG YB400 and AR8200MK3 silently continued to watch further events from the floor.
It was true. During the reception with the general outside antenna
the better HF transceiver and the sixty dollar Chinese “soap box” received
almost the same. The signal passing through was saturating; in most
bands the level of the received “voices” pushed the needle of the S-meter
of the transceiver on the red end of the scale. Switching on the attenuator
in the DE1103 (according to the measurements its attenuation is about
17 dB) was desirable, but in fact was only seldom needed. When there
were doubts about generation of overload signals, like suspected increase
of the general level of noise, the use of the attenuator returned the
reception to comfortable levels.
Simultaneous reception with the common outside antenna: 10Khz away from a strong station, the difference in the signal level is more than 60 dB; in the dynamics the DE1103 has only weak “tails” in the peaks of the modulation of the strong signal.
I furrowed the shortwave band, tuning in different broadcast and amateur stations with both receivers, evaluating the reception quality here and there, but the result looked as obvious as it seemed unreal at the beginning. After a while I had to fully believe this small guy.
But it is known that the ideal receiver does not exist yet, and the
DE1103 has its own problems too. These are the mirrors IF chanels of
the strong stations. Some of them are in the TV reception band, and
the experienced ear can hear in particular points of SW bands a low
but characteristic sound of the carrier’s mirror or “tails” of the sound
carrier. Regarding this parameter the E1103 does not look worse than
his friends; these effects look the same even in the more known and
expensive receivers. And “the permeation” of the mirror channel of the
second IF is bigger, but we will talk more about it in the next part
of the review.
This part of the review is basically dedicated to the amateurs who want to look inside and to those who want to improve their DE1103. People who are not interested in the “inside world” of the technique, can skip this part and go to the conclusions right away.
A quick look on the board of the receiver confirmed that like other modern portable “digitals”, DE1103 is built according to the schematic of “upper” transform with two intermediate frequencies. The general schematic is more complicated for the SONY ICF-7600GR and GRUNDIG YB400. I will not describe the schematic and knots, but I will stop in the most interesting and important (according to my opinion) moments of DE1103.
The body is built in two parts. In the first one the analog circuit and the powering system are placed.
The reception in the 100-1710 Khz band is realized with the internal magnetic antenna.
The second part contains the circuit of the processor with the display and the control buttons. Here is placed the 77mm dynamic speaker too.
To remove the RF/IF board of DE1103 you need to de-solder the output for the inductor of the ferrite antenna from the soldering points in the circuit and unscrew some screws in the back side of the lid of the main body.
I advise you to mark the place of output for the antenna inductors in the circuit.
If you incorrectly reattach the inductors in the circuit (the one in
the first picture in the left side of the ferrite antenna bar), it is
possible to have a generation from the RF amplifier. This negative phenomenon
may not attract attention right away, and can be seen as an increase
of the “reception noise” and a decrease of the sensitivity of the receiver
adding parasite reception points.
From the study of the circuits I found out surprising features
1. With the attachment of the outside antenna into the antenna jack, the whip antenna is fully excluded and after it the RF amplifier of the AM bands (to the envy of the owners of YB400’s and 7600GR’s). In this way the signal from the entry point through the switched attenuator and the LPF (low-pass filter) goes into the balanced mixer (realized through two single gate FET’s, the schematic of the mixers being almost exactly the same as for YB400’s and 7600GR’s). Here is the reason for the excellent stability in overload and intermodulation for the DE1103! At the same time in the other receivers, the entry cascade of the RF amplifier is always on, and the outside antenna is attached to it instead of the whip; the DEGEN designers minimized the signal amplification and the result was immediately attained.
The data about the measurements of the sensitivity in the table above are taken from antenna jack. During the reception with the whip antenna, the signal is further amplified by the entry cascade (about 10 dB), making the DE1103 very highly sensitive to work even with the shortened whip antenna; this is very good.
2. A integral band pass filter is set at the input of the FM section, such that I haven’t seen in the other small receivers. The right solution for the input circuit makes it work flawlessly.
3. The good selectivity for adjacent channels in LW/MW/SW bands is due to good filters of the second intermediate frequency.
IF filters in the DE1103 are chosen wonderfully. Their difference during switching from one to the other is easily understood by sound. The inscriptions on the bodies of the filters are R50J and 450H. They correspond to the specified band passes, 3 and 6 Khz respectively. DEGEN specifies the value of 4 Khz for the band pass of the “narrow” filter in the DE1103. Therefore, the value of the band pass of 4 Khz has a reserve on the better side. Now the difference in selectivity with the YB400 is understood; in the case of YB400 the narrow filter is marked 50I, and this is a true 4 Khz one.
But there is bad news too. There is a mandatory test about the parasite reception of mirror signals in the second intermediate frequency (+ 900 Khz above the tuning frequency, the intermediate frequency of the receiver being 450 Khz), which characterizes the suppression of the signals in the opaque part of the filter of the first intermediate frequency. Here the newcomer surrendered having a test result of -42 dB. His opponent in this test, the YB400, did much better (-60 dB).
The practial importance of the selective properties of the first quartz filter are important in the real reception to keeping out the strong signals that have a frequency double of the second IF (900 Khz) above the tuning frequency of the receiver. Precisely, this “Achilles heel” of the DE1103 is seen during reception with the outside antenna. There was a weak and parasite reception of the powerful radiostations that were 900 Khz above the tuning frequency of the receiver.
The schematic of the first quartz filters is identical with the one for YB400’s and 7600GR’s, therefore the difference in the reception results can be explained by the quality of the filter used and/or the topology of the assembly.
The author has tested many times the screening over the printed circuit where
the filter is, to prevent the “leakage in air”. In the case of DE1103
the screening reduced the leakage for about 8 dB outside the filter’s
The search for the cause of the distortion of the signal in the SSB
reception led me into the IC of the PLL.
Approaching the hand in the part of the board where the IC located,
it influenced the quality of the signal output of the PLL. A distortion
of the sound appeared.
A simple screening of this part of the circuit eliminated the defect:
Unfortunately, the PLL of DE1103 has a birth defect, which is hard
to correct with simple means. This is the insufficient filtration of
the control voltage for VCO. This schematic chosen by the DEGEN engineers
is a simple passive RC filter that substitutes the charging transistor
and filter circuit (that are present in YB400’s and 7600GR’s). Because
of this, you can hear the “blip-blip” during tuning with the tuning
knob in the quiet parts of the SW bands. A continuous vibration starts
in the filter circuit until the full tuning is achieved. Besides, the
output signal from VCO has a weak low frequency parasite FM. This defect
becomes more noticeable with the increase of the reception frequency;
in the frequencies above 25Mhz even an untrained ear can hear the distortion<
of the SSB that reminds you of a light roar. This is a mistake in the
calculation of PLL by not considering the true control characteristic
Why be so severe with the Chinese – you can ask? But the same YB400
is an exemple of the good job in the PLL schematic by just changing
it a little. And the work of the PLL is the first to stand out in an
SSB receiver. Since I had access to the schematic, let’s have a quick
look at characteristic of LPF in the 100 Khz – 29.999 Mhz from the antenna
jack to the mixer input.
LPF is made of two inductors and some capacitors (on the back side of the circuit).
In each cell of the analyzer are 10 Mhz horizontal and 10 dB vertical:
You can see the typical “fall” of the characteristitcs of the input filter starting from 12 Mhz.
This is the explanation of the substantial decrease of the sensitivity
in the higher frequencies of the SW band (up to -10 dB at 29Mhz). Compare
this with the results of the measurements for the real sensitivity earlier.
Is this a miscalculation of the DEGEN designers or a lack of the real
testing? This flaw needs to be fixed. More about it the next time.
Re-reading the review and remembering the test steps, I found similarities with a boxing game. We watched a good fight!
We saw everything; the fighters were shown in public. We saw their eye contact, where the pretty unknown challenged the champions. We saw multiple punches exchanged, where the newcomer caught his opponents out of guard, but he himself received some punches that could have been avoided if the coaches paid a little more attention to the training...
From the beginning the pretendent started well, showing preparation and technique worth of respect. And if until the end the outcome was uncertain and the issue about the winner stayed open, the sudden knock out of the competitor in the last working test with the outside antenna put the all the dots over “i-s”.
The decive victory came when nobody expected, but was neat and according to the rules.
As it usually happens we like the old champions and cover their weaknesses with previous glory. But the end of every star is a new star. This time the sympathetic boy from the Chinese province played fairly and honestly.
Let’s hope that the winner does not blame us for the harsh exam that we submitted him. If DEGEN does not want to be one of the several “soap boxes” in the windows of the stores, it has to be up to the heights of their competitors. And it did it.
What i liked:
- compact size and small weight
- construction design, sturdiness
- quality of assembly
- the convenience of the manual tuning
- automatic back lighting of the buttons and the display
- the big quantity of memories
- high sensitivity
- superior overload parameters in LW/MW/SW bands
- choice and characteristics of the filters of intermediate frequency
- The presence of the line out jack
- good sound
- good quality of the assembly
- Rechargable battery powering with possibility to charge batteries inside the receiver
- Complete features
What i didn`t like:
- inconvenience of the volume adjustment
- Noise and instability of the PLL schematic, instability of settings
- Fixed tuning step
- high power consumption
- The absence of the second clocks simultaneously with the tuning frequency
- the presence of low levels of mirror reception channels (according to professional standards)
After I finished the test of the DE1103 I understood that now I have a receiver that I dreamed. Small and light, sturdy and stylish, powered with rechargeable batteries and excellent reception characteristics. You can take it in the train and listen with the whip antenna, or attaching a good antenna, receive “live” ether, without fearing to lose its fullness in the noise of overload.
Show me another receiver with the same choice of features priced $90 (here in Russia, abroad a new DE1103 is sold for $55!) to make me reconsider its leadership position in this class.