Post by Oscar Bravo on Oct 27, 2018 15:43:43 GMT 2
Features and Specifications:
FM: 87.5–108 MHz/64-108 MHz With FM RDS Stereo/Mono Switchable .1/.01 MHz Tuning Steps
MW: 520-1710 KHz/520-1620 KHz 10K/9K/1K Steps
LW: 150 – 450 KHz 9K/1K Steps
SW: 1711 – 29999 KHz 5K/1K Steps
Air: 118-137 MHz .25/.001 MHz Steps
SSB With Fine Tuning Control (Fine Tuning works on all bands)
Tune via Knob or Up/Down Buttons with ATS
Volume Thumbwheel
Direct Frequency Entry
Lock Mode
Clock/Alarm/Sleep Timer
MW/SW Bandwidths: 7) 6K, 4K, 3K, 2.5K, 2K, 1.8K and 1K
SSB Bandwidths: 6) 4K, 3K, 2.2K, 1.2K, 1K and 500 Hz
500 Memories
Switchable Display: Time (Default), Signal Strength/Signal To Noise ratio, Temp (Fahrenheit or Centigrade) and Alarm Time.
Illumination Can Be Automatic or locked on
Squelch Control (Works On all bands which is unusual)
Earphone Jack 3.5mm
Ext Antenna Jack 3.5mm for SW/FM/Air
Fast/Slow/Stop (Lock) Tuning Speeds
You can also defeat the Beep Tone by depressing the #5 Beep button with the radio off.
Light Button turns on the dial illumination permanently…a nice feature.
Reset Button
Power Source: USB rechargeable 18650 Li-ion 3.7v battery
Micro USB Cable and Carry Case Supplied
It is interesting to note that although many radios use the same Silicon labs Si4735 series DSP Chips, these chips offer many features which may not all be available in any one radio, as well as many settings the manufacturer can adjust to customize many details of operation. Add to this the fact that every radio will have its own ferrite rod AM antenna, SW/FM/Air whip antenna and speaker which will affect reception and sound quality and you can see that two radios can use the same DSP chip and yet be quite different in many ways. There are also, of course, many areas where performance will be identical…my own experience suggests that SW/FM/Air reception tends to be similar when the whip antennas are similar while AM reception will be different depending on the size of the built-in ferrite rod AM antenna.
FM: 87.5–108 MHz/64-108 MHz With FM RDS Stereo/Mono Switchable .1/.01 MHz Tuning Steps
MW: 520-1710 KHz/520-1620 KHz 10K/9K/1K Steps
LW: 150 – 450 KHz 9K/1K Steps
SW: 1711 – 29999 KHz 5K/1K Steps
Air: 118-137 MHz .25/.001 MHz Steps
SSB With Fine Tuning Control (Fine Tuning works on all bands)
Tune via Knob or Up/Down Buttons with ATS
Volume Thumbwheel
Direct Frequency Entry
Lock Mode
Clock/Alarm/Sleep Timer
MW/SW Bandwidths: 7) 6K, 4K, 3K, 2.5K, 2K, 1.8K and 1K
SSB Bandwidths: 6) 4K, 3K, 2.2K, 1.2K, 1K and 500 Hz
500 Memories
Switchable Display: Time (Default), Signal Strength/Signal To Noise ratio, Temp (Fahrenheit or Centigrade) and Alarm Time.
Illumination Can Be Automatic or locked on
Squelch Control (Works On all bands which is unusual)
Earphone Jack 3.5mm
Ext Antenna Jack 3.5mm for SW/FM/Air
Fast/Slow/Stop (Lock) Tuning Speeds
You can also defeat the Beep Tone by depressing the #5 Beep button with the radio off.
Light Button turns on the dial illumination permanently…a nice feature.
Reset Button
Power Source: USB rechargeable 18650 Li-ion 3.7v battery
Micro USB Cable and Carry Case Supplied
It is interesting to note that although many radios use the same Silicon labs Si4735 series DSP Chips, these chips offer many features which may not all be available in any one radio, as well as many settings the manufacturer can adjust to customize many details of operation. Add to this the fact that every radio will have its own ferrite rod AM antenna, SW/FM/Air whip antenna and speaker which will affect reception and sound quality and you can see that two radios can use the same DSP chip and yet be quite different in many ways. There are also, of course, many areas where performance will be identical…my own experience suggests that SW/FM/Air reception tends to be similar when the whip antennas are similar while AM reception will be different depending on the size of the built-in ferrite rod AM antenna.
Link
Introduction
Xhdata D-808 is a new portable world band radio receiver released in 2017. Now it can be purchased via several Chinese on-line radio shops for about 75-85 US$. The receiver is built on DSP technology, so it has most of drawbacks and advantages specific for the digital signal processing (yes, soft-mute too). By the way, it is my first DSP receiver, I have never used such type of radios before.
D-808 has also at least one twin (Digitech AR1780 more known in Australia and North America). The difference between these two models is in external design, buttons configuration, colour of LCD backlight and type of used accumulator batteries for power supply. According to some information in Internet, the both receivers are operated by Silicon Labs® Si4735 DSP Radio chip, and can rather be clones of some DSP Etons.
Overall impression
Together with the radio I received: nice specific bag, external antenna (piece of wire 3 meters long with 3.5 mm connector), micro-USB charge cable, 18650 Li-ion battery and English user manual (I’m happy that Radiwow shop is sending English manuals instead of russian ones to Ukraine by default, it is a right decision while Ukrainian translation is absent, indeed).
18650 Li-ion battery is quite pleasant feature of my new device: now it’s not necessary to pull the accumulators out from receiver and charge them in external intelligent charger, all I need is to connect receiver to some USB port using supplied micro-USB cable. The time of persistent operation after full charging cycle is pretty long. However, this type of autonomous power supply is sensitive to low temperatures (frost), and this circumstance must be taken into account by outdoor DXers, like me, especially during winter season. The “Warning” section of user manual even contains respective paragraph: · Only operate within specified temperature range (0 °C to 40 °C).
Like most of Tecsuns, Xhdata D-808 has built-in thermometer with indication in °C or °F. The temperature is always appearing on the receiver’s indicator first at switching D-808 on, which is quite strange and annoying, because signal level and signal-to-noise ratio are probably much more interesting values for DXers. And one have to press “Display” button three times for dBμ and dB indication. Fortunately, this indication mode is remaining after switching of bands, frequencies and reception modes. The thermometer of my device is relatively precise, I have compared its indication with one of liquid thermometers of my home psychrometer.
D-808 is more pocket-friendly than DE1103, as its size is only 150×90×32 mm against Degen’s 165×102×28 mm, and it is more lightweight: only 265 g against Degen’s 300 g (without batteries, according to user manuals). Nevertheless, sound of D-808 loudspeaker is quite pleasant and even has some bass component, moreover, it is really loud at maximum volume. By the way, the volume control is analog in this receiver (variable resistor).
Well, let’s look at the frequency ranges, reception modes and tuning steps available in this device:
LW (deactivated by default, but can be switched on, AM/LSB/USB): 150 – 450 kHz (0.01(SSB) or 1 or 3 kHz step)
MW (9 kHz step mode, AM/LSB/USB): 522 – 1620 kHz (0.01(SSB) or 1 or 9 kHz step)
MW (10 kHz step mode, AM/LSB/USB): 520 – 1710 kHz (0.01(SSB) or 1 or 10 kHz step)
SW (incl. 11, 13, 15, 16, 19, 22, 25, 31, 41, 49, 60, 75, 90, 120 meter bands, AM/LSB/USB): 1711 – 29999 kHz (0.01(SSB) or 1 or 5 kHz step)
FM (64.0M mode, WFM only): 64.00 – 108.00 MHz (10 or 100 kHz step)
FM (87.5M mode, WFM only): 87.50 – 108.00 MHz (10 or 100 kHz step)
FM (87.0M mode, WFM only): 87.00 – 108.00 MHz (10 or 100 kHz step)
FM (76.0M mode, WFM only): 76.00 – 108.00 MHz (10 or 100 kHz step)
AIR (AM only): 118.00 – 137.00 MHz (1 or 25 kHz step)
The choice is quite wide for the radio of such class! Presence of OIRT FM band is a great benefit (one of that which induced me to buy D-808), not every pocket receiver has this great option. Also AIR band spotters will be glad to find familiar frequencies and squelch function there, but 108.00 – 137.00 would be better (navaids are also interesting DX-targets).
Why fast step on LW is 3 kHz instead of habitual 9 kHz? I guess, designer took into account listeners in Mongolia, where is broadcasting on non-standard LW frequencies of 164, 209 and 227 kHz. These channels are still aliquant of 3, but 1 kHz difference is not an issue.
Frequencies between 1621 and 1710 kHz inclusive are available in 10 kHz MW step mode only. E.g.: you can listen to 1690 kHz in 10 kHz MW step mode and save it into some memory cell, but you cannot load it then in 9 kHz MW step mode from this cell. Thus, it is some inconvenience for those European DXers who like to listen to both European MW pirates and official MW broadcasters. This refers to 520 and 521 kHz too.
Frequencies between 451 and 519 kHz inclusive are unavailable in this receiver at all, this fact must be taken into account by NDB, 630 MB HAM and NAVTEX “hunters”. By the way, this RX is not suitable for the mentioned categories of DXers also by some other reason, which is described below.
Xhdata D-808 has switchable 6/7-stage bandwidth filters (for LW, MW, SW and AIR bands): 1, 1.8, 2, 2.5, 3, 4, 6 kHz for AM and 0.5, 1, 1.2, 2.2, 3, 4 kHz for LSB/USB. But I think, it is an excessiveness: for most DX-aims 2 and 4 kHz are enough in AM mode and 2.2 kHz is probably optimal for LSB/USB. So, the wide choice of bandwidths is not decisive superiority in comparison to DE1103 with its simple “narrow-wide” switch. Also for some obscure reason 2.5 kHz sounds really almost the same or even slightly wider than 3 kHz for me in AM mode, the same oddity is for 1 and 1.2 kHz in LSB/USB (I’m not sure, estimated by ear only).
Reception on LW and MW is possible with built-in ferrite rod. Telescopic whip or external antenna are for SW, FM and AIR bands. Pity, built-in telescopic whip cannot be used for reception on medium waves, like in good old Degen DE1103. The length of telescopic antenna is only 67 cm, and it is not long enough, in my opinion (DE1103 has 92 cm long one).
Another great benefit which induced me to buy this receiver is RDS-decoder, very helpful for FM DXing. Display of PS, Radiotext (static only), date/time and PTY are available. RDS module is quite fast and it decodes PS information easily for all CCIR FM stations of Kyiv except Radio ROKS on 103.6 kHz, for which PS is being decoded but very rarely by some unclear reason. It is especially strange because Radio ROKS has may be the highest level of RDS component in the FM spectrum among all local stations and its signal as strong as other stations here (at the same time no any problem with PTY decoding for ROKS). Sometimes it can even decode RDS of Radio Liuks from Bila Tserkva (3 kW ERP, about 70 km distance), however I cannot say anything about its real sensitivity because I have no other receivers with RDS-option to compare. Seems to work well.
Xhdata D-808 is also equipped by many additional features:
Sleep timer: 15, 30, 45, 60, 90 and 120 min time intervals are available.
Time and alarm: time can be synchronized with RDS data of FM stations or adjusted manually, alarm has two modes: by switching radio on or by beeping.
Tuning knob (encoder) with manually switchable fast/slow step: the knob also works as a button, you can press it to change tuning step, lock it or set a squelch level
199-stage fine tuning for LSB/USB reception (encoder): up to ± 1 kHz approximately, about 10 Hz tuning step.
9-stage squelch function
Up and down tuning buttons
Keyboard and tuning knob lock feature: you can also lock only knob
Temperature/time/alarm/signal strength (in dBμ) and SNR (in dB) display feature
Stereo/mono reception on FM band switch
Direct frequency input
SW bands switch: 11, 13, 15, 16, 19, 22, 25, 31, 41, 49, 60, 75, 90, 120 meters
500 memory cells: 100 cells for each band (LW, MW, SW, FM, AIR) divided into 10 memory banks, the cells cannot be flipped through by any way, all stored frequencies can only be loaded by direct bank number/cell number input. Besides frequency, receiver remembers also stereo or mono selection (FM) and bandwidth selection (LW, MW, SW, AIR) but can’t remember a reception mode.
Bands scan feature: on SW scanning is possible only in boundaries of BC bands (11, 13, 15, 16, 19, 22, 25, 31, 41, 49, 60, 75, 90, 120 meters), so, e.g. you cannot scan into CB or most of HAM bands.
ATS (Auto Tuning System) feature: receiver scans band(s) and stores frequencies of found stations into memory cells. On SW scanning is possible only in boundaries of BC bands
Button beeps feature
Backlight of LCD: continuous or automatic, cannot be switched completely off. The color of lighting is bluish.
3.5 mm earphone jack
3.5 mm external antenna jack
Back stand
Reset hole: I have never used it so far.
And yes, there is no attenuator in this list. It is not a substantial shortage if you are going to use this receiver with only its built-in antennas, however this option is absolutely necessary when you want to connect external antennas to. Anyway, each radio with external antenna jack must have it! And it is very strange that designer does not provide even primitive attenuator, because there is a lot of free space inside.
Linear output jack would also be a great gift for everybody who is interested in digital signals, Weather FAX or SSTV decoding, but such option is not included.
Performance
First, I would mention the most considerable disadvantage of Xhdata D-808: sound muting after frequency change. This behavior is typical for many DSP-receivers (and even some analog ones) on all reception modes, but it is extremely annoying for those listeners who like to surf radio waves or to search something on specific frequency range. The time of complete restoring can be up to ~1 sec, and it is especially noticeable on long waves, medium waves and CB frequencies. There are less troubles on FM, however this idiotic muting still makes any travel across radio waves very uncomfortable. You can ignore this “bad feature” only if you know exactly what and where you want to listen. One can also use band scan option instead, but it is not a solution for real DXers: band scan will always skip weak signals and it is possible in boundaries of BC bands only (on SW).
Here are estimation results of the most important performance capabilities of Xhdata D-808 in comparison with my old Degen DE1103 (analog version, the same as Kaito KA1103).
Important notices: 1) Length of telescopic whip antennas was the same for both receivers: 67 cm. 2) I’m not interested in loudspeaker or any acoustic performance comparison here, most of attention was paid to such parameters as sensitivity, adjacent channel selectivity, dynamic range, spurious channels etc. thus all the recordings were made using audio cable and laptop PC. 3) Degen’s attenuator was off in all cases. 4) All the comparisons were realized for consecutive recordings with minimum possible time intervals between. 5) This is only comparative estimation, not a measuring, so here are no exact or even inexact values of respective parameters.
Xhdata D-808 is a new portable world band radio receiver released in 2017. Now it can be purchased via several Chinese on-line radio shops for about 75-85 US$. The receiver is built on DSP technology, so it has most of drawbacks and advantages specific for the digital signal processing (yes, soft-mute too). By the way, it is my first DSP receiver, I have never used such type of radios before.
D-808 has also at least one twin (Digitech AR1780 more known in Australia and North America). The difference between these two models is in external design, buttons configuration, colour of LCD backlight and type of used accumulator batteries for power supply. According to some information in Internet, the both receivers are operated by Silicon Labs® Si4735 DSP Radio chip, and can rather be clones of some DSP Etons.
Overall impression
Together with the radio I received: nice specific bag, external antenna (piece of wire 3 meters long with 3.5 mm connector), micro-USB charge cable, 18650 Li-ion battery and English user manual (I’m happy that Radiwow shop is sending English manuals instead of russian ones to Ukraine by default, it is a right decision while Ukrainian translation is absent, indeed).
18650 Li-ion battery is quite pleasant feature of my new device: now it’s not necessary to pull the accumulators out from receiver and charge them in external intelligent charger, all I need is to connect receiver to some USB port using supplied micro-USB cable. The time of persistent operation after full charging cycle is pretty long. However, this type of autonomous power supply is sensitive to low temperatures (frost), and this circumstance must be taken into account by outdoor DXers, like me, especially during winter season. The “Warning” section of user manual even contains respective paragraph: · Only operate within specified temperature range (0 °C to 40 °C).
Like most of Tecsuns, Xhdata D-808 has built-in thermometer with indication in °C or °F. The temperature is always appearing on the receiver’s indicator first at switching D-808 on, which is quite strange and annoying, because signal level and signal-to-noise ratio are probably much more interesting values for DXers. And one have to press “Display” button three times for dBμ and dB indication. Fortunately, this indication mode is remaining after switching of bands, frequencies and reception modes. The thermometer of my device is relatively precise, I have compared its indication with one of liquid thermometers of my home psychrometer.
D-808 is more pocket-friendly than DE1103, as its size is only 150×90×32 mm against Degen’s 165×102×28 mm, and it is more lightweight: only 265 g against Degen’s 300 g (without batteries, according to user manuals). Nevertheless, sound of D-808 loudspeaker is quite pleasant and even has some bass component, moreover, it is really loud at maximum volume. By the way, the volume control is analog in this receiver (variable resistor).
Well, let’s look at the frequency ranges, reception modes and tuning steps available in this device:
LW (deactivated by default, but can be switched on, AM/LSB/USB): 150 – 450 kHz (0.01(SSB) or 1 or 3 kHz step)
MW (9 kHz step mode, AM/LSB/USB): 522 – 1620 kHz (0.01(SSB) or 1 or 9 kHz step)
MW (10 kHz step mode, AM/LSB/USB): 520 – 1710 kHz (0.01(SSB) or 1 or 10 kHz step)
SW (incl. 11, 13, 15, 16, 19, 22, 25, 31, 41, 49, 60, 75, 90, 120 meter bands, AM/LSB/USB): 1711 – 29999 kHz (0.01(SSB) or 1 or 5 kHz step)
FM (64.0M mode, WFM only): 64.00 – 108.00 MHz (10 or 100 kHz step)
FM (87.5M mode, WFM only): 87.50 – 108.00 MHz (10 or 100 kHz step)
FM (87.0M mode, WFM only): 87.00 – 108.00 MHz (10 or 100 kHz step)
FM (76.0M mode, WFM only): 76.00 – 108.00 MHz (10 or 100 kHz step)
AIR (AM only): 118.00 – 137.00 MHz (1 or 25 kHz step)
The choice is quite wide for the radio of such class! Presence of OIRT FM band is a great benefit (one of that which induced me to buy D-808), not every pocket receiver has this great option. Also AIR band spotters will be glad to find familiar frequencies and squelch function there, but 108.00 – 137.00 would be better (navaids are also interesting DX-targets).
Why fast step on LW is 3 kHz instead of habitual 9 kHz? I guess, designer took into account listeners in Mongolia, where is broadcasting on non-standard LW frequencies of 164, 209 and 227 kHz. These channels are still aliquant of 3, but 1 kHz difference is not an issue.
Frequencies between 1621 and 1710 kHz inclusive are available in 10 kHz MW step mode only. E.g.: you can listen to 1690 kHz in 10 kHz MW step mode and save it into some memory cell, but you cannot load it then in 9 kHz MW step mode from this cell. Thus, it is some inconvenience for those European DXers who like to listen to both European MW pirates and official MW broadcasters. This refers to 520 and 521 kHz too.
Frequencies between 451 and 519 kHz inclusive are unavailable in this receiver at all, this fact must be taken into account by NDB, 630 MB HAM and NAVTEX “hunters”. By the way, this RX is not suitable for the mentioned categories of DXers also by some other reason, which is described below.
Xhdata D-808 has switchable 6/7-stage bandwidth filters (for LW, MW, SW and AIR bands): 1, 1.8, 2, 2.5, 3, 4, 6 kHz for AM and 0.5, 1, 1.2, 2.2, 3, 4 kHz for LSB/USB. But I think, it is an excessiveness: for most DX-aims 2 and 4 kHz are enough in AM mode and 2.2 kHz is probably optimal for LSB/USB. So, the wide choice of bandwidths is not decisive superiority in comparison to DE1103 with its simple “narrow-wide” switch. Also for some obscure reason 2.5 kHz sounds really almost the same or even slightly wider than 3 kHz for me in AM mode, the same oddity is for 1 and 1.2 kHz in LSB/USB (I’m not sure, estimated by ear only).
Reception on LW and MW is possible with built-in ferrite rod. Telescopic whip or external antenna are for SW, FM and AIR bands. Pity, built-in telescopic whip cannot be used for reception on medium waves, like in good old Degen DE1103. The length of telescopic antenna is only 67 cm, and it is not long enough, in my opinion (DE1103 has 92 cm long one).
Another great benefit which induced me to buy this receiver is RDS-decoder, very helpful for FM DXing. Display of PS, Radiotext (static only), date/time and PTY are available. RDS module is quite fast and it decodes PS information easily for all CCIR FM stations of Kyiv except Radio ROKS on 103.6 kHz, for which PS is being decoded but very rarely by some unclear reason. It is especially strange because Radio ROKS has may be the highest level of RDS component in the FM spectrum among all local stations and its signal as strong as other stations here (at the same time no any problem with PTY decoding for ROKS). Sometimes it can even decode RDS of Radio Liuks from Bila Tserkva (3 kW ERP, about 70 km distance), however I cannot say anything about its real sensitivity because I have no other receivers with RDS-option to compare. Seems to work well.
Xhdata D-808 is also equipped by many additional features:
Sleep timer: 15, 30, 45, 60, 90 and 120 min time intervals are available.
Time and alarm: time can be synchronized with RDS data of FM stations or adjusted manually, alarm has two modes: by switching radio on or by beeping.
Tuning knob (encoder) with manually switchable fast/slow step: the knob also works as a button, you can press it to change tuning step, lock it or set a squelch level
199-stage fine tuning for LSB/USB reception (encoder): up to ± 1 kHz approximately, about 10 Hz tuning step.
9-stage squelch function
Up and down tuning buttons
Keyboard and tuning knob lock feature: you can also lock only knob
Temperature/time/alarm/signal strength (in dBμ) and SNR (in dB) display feature
Stereo/mono reception on FM band switch
Direct frequency input
SW bands switch: 11, 13, 15, 16, 19, 22, 25, 31, 41, 49, 60, 75, 90, 120 meters
500 memory cells: 100 cells for each band (LW, MW, SW, FM, AIR) divided into 10 memory banks, the cells cannot be flipped through by any way, all stored frequencies can only be loaded by direct bank number/cell number input. Besides frequency, receiver remembers also stereo or mono selection (FM) and bandwidth selection (LW, MW, SW, AIR) but can’t remember a reception mode.
Bands scan feature: on SW scanning is possible only in boundaries of BC bands (11, 13, 15, 16, 19, 22, 25, 31, 41, 49, 60, 75, 90, 120 meters), so, e.g. you cannot scan into CB or most of HAM bands.
ATS (Auto Tuning System) feature: receiver scans band(s) and stores frequencies of found stations into memory cells. On SW scanning is possible only in boundaries of BC bands
Button beeps feature
Backlight of LCD: continuous or automatic, cannot be switched completely off. The color of lighting is bluish.
3.5 mm earphone jack
3.5 mm external antenna jack
Back stand
Reset hole: I have never used it so far.
And yes, there is no attenuator in this list. It is not a substantial shortage if you are going to use this receiver with only its built-in antennas, however this option is absolutely necessary when you want to connect external antennas to. Anyway, each radio with external antenna jack must have it! And it is very strange that designer does not provide even primitive attenuator, because there is a lot of free space inside.
Linear output jack would also be a great gift for everybody who is interested in digital signals, Weather FAX or SSTV decoding, but such option is not included.
Performance
First, I would mention the most considerable disadvantage of Xhdata D-808: sound muting after frequency change. This behavior is typical for many DSP-receivers (and even some analog ones) on all reception modes, but it is extremely annoying for those listeners who like to surf radio waves or to search something on specific frequency range. The time of complete restoring can be up to ~1 sec, and it is especially noticeable on long waves, medium waves and CB frequencies. There are less troubles on FM, however this idiotic muting still makes any travel across radio waves very uncomfortable. You can ignore this “bad feature” only if you know exactly what and where you want to listen. One can also use band scan option instead, but it is not a solution for real DXers: band scan will always skip weak signals and it is possible in boundaries of BC bands only (on SW).
Here are estimation results of the most important performance capabilities of Xhdata D-808 in comparison with my old Degen DE1103 (analog version, the same as Kaito KA1103).
Important notices: 1) Length of telescopic whip antennas was the same for both receivers: 67 cm. 2) I’m not interested in loudspeaker or any acoustic performance comparison here, most of attention was paid to such parameters as sensitivity, adjacent channel selectivity, dynamic range, spurious channels etc. thus all the recordings were made using audio cable and laptop PC. 3) Degen’s attenuator was off in all cases. 4) All the comparisons were realized for consecutive recordings with minimum possible time intervals between. 5) This is only comparative estimation, not a measuring, so here are no exact or even inexact values of respective parameters.
Link
Bonus
and ...
