SIHUADON D808 Portable Radio Transistor AM FM SW LW SSB Air Band Multiband Radio Loudspeaker Alarm Clock Sleep Timer Black

Product Information

Some report loss of sensitivity after changing betwween RF bands.This seems to be a firmware bug, as it can be fixed by doing a power off/power on sequence, or remove and insert the battery, or doing a Reset (use a clip to insert in the Reset hole). So the manufacturer have cut production costs by eliminating costly LC trimmers and active components of the Pre-Scaler and DC-DC converter, reduced the alignment requirements at the assembly line, and potentially have reduced some internal noise coming from the MCU/Display into the DSP, at the cost of offering a radio with lesser ability to reject strong spurius RF signals. The XHDATA D-808 FM Stereo/LW/MW/SW-SSB AIR RDS Synthesized Receiver is supplied with a succinctOperation Guide that may not cover all the details of the radio operation behavior.

Anti-interference: R-108 radio with anti-interference switch, can adapt to strong radio interference environment. AM broadband, narrowband selection. Broadband can improve the sound quality of strong signal broadcast programs, while narrowband can improve the anti-interference ability of adjacent channels. A DW01A (IC2) & a 82015A MOSFET (IC1) do overcharge protection, while a TP4056 (U2) charges the Li-Ion battery at 400mA until it reaches 4.2V. I am currently located in the Northeast of Portugal, at an altitude of about 1000 meters, and I can receive radio transmission signals from the various passenger planes that fly over the area, using the telescopic antenna and being indoors at the window. SW band below 3 MHz have been repeatedly reported to show lower sensitivity, but above that it competes with other similar class radios. This seems to be a design issue in the RF analog input stage, not a DSP issue.The squelch also works adequately in my opinion. Set it level 1 and it will not mute the audio due to the noise floor inside house (around 12dBu), but at level 2 it would mute it; then the radio is able to unmute the audio for signals as low as 25dBu. After around 4 hours charging, the battery level indicator movement stopped and showed 3 static bars. The battery had then 4.15V. Initially I thought that this behavior wasrelated to a defective component,but now that I have my unit (new version 2021), I am not so sure.As the volume is a pure analog potentiometer, the noise must be generated inside the CS4863 (LM4863 equivalent) audio power amplifier IC. Here are some of the behaviors detected by several owners and testers since this model was released:​ Some have reported that the squelch is not fast enough to unmute resulting in loss of the initial conversation. I can confirm this to be true, but it loses just a small fraction of a second, not really an issue.

Doingmanual tuning across RF bands results in muting/chuffing sounds when changing eachRF step.This seems to be a design characteristicof DSP based radios. In this model the volume drop can be reduced by seleccting the Slow tuning mode. Looking to the publicly available pictures, extensive changes were made in the circuit diagram and PCB layout of the Receiver board. On the other hand, the AVDbridged mode differential gain configured on the D-808 is too high, generating lots of noise, and that may also be increasing these shudown/turn-on noises as well. LW band seems to show poor sensitivity on DSP radios like this model category, due to a poor design of the RF analog passive components that favors the MW band.Some owners have reported a fast battery depletion even when the radio is powered off, but this seems to be a fault developed with usage or a manufacturing defect. Due to product quality problems within 1-3 months of receiving the product, we can replace it with a new one, but the customer pays for the logistics costs incurred. My 2021 unit present these transitory noises. I wonder if the muting system is not being enabled by the MCU firmware. Bug or hardwaredesign fault?

In my 2021 unit, I can not confirm this behavior seen in the older original model of 2018. The radio is able to find signals with just 30dBu and 4dB S/N ratio. 30dBu may look like a high level signal but the radio is by the window inside the house using the telescopic antenna and the noise floor here is around 20 to 25 dBu. SIHUADON R-108 not only has a manual search mode. It also has an Auto-Tuning Memory (ATS) mode. Press and hold “BAND” to automatically search for stations with stronger signals and store them in the radio. This mode greatly saves the time spent manually storing the station. For stations that do not receive strong signals, it is suitable for manual storage. Dual mode storage station for you to choose from. Telescopic antenna - Last section (with tip) detached from the rest. Also, the antenna mounting seems to be fragile, requiring great care when rotating it, as it can break the plastic support. Gone is the RF front-End with the 4-Sub-Bands pre-scaler using four LC trimmers for proper alignment and better spurius strong signals rejection, being replaced by common LCR fixed values networks using SMD components. My 2021 unit came with 3.81V in the battery (still a XHDATA 2000mAh device) and the battery level indicator had 2 bars.Functional: Alarm function, sleep mode, and the time can be set and displayed in the off state. The sleep timer setting can be automatically turned off according to your lifestyle settings. R108 radio can be placed on the bedside, get up in the morning, enjoy the wake-up service of the radio, and watch the time with an open eye. When you brush your teeth, you can listen to the radio and keep up to date with the news. This audio stage noise is more audible thru the speaker than on earphones, what seems to make no sense. But when looking to the circuit we see the reason. The earphones are driven thru a series RC network with 100uF and 100Ohm. Depending on the earphones impedance, the noise will be stronger for higher impedance units. However the common earphones would present 32 Ohm, a low value when compared with the series 100 Ohm resistor. Despite being mentioned in the Operations Guide, there is no key for that. The D-808 was designed with automatic charging and management of the installed battery.