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

Product Information

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. 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.

The audio components section was rearranged and the DC-DC converter to supply voltage to the Pre-Scaler varicap is not visible anymore, so it seems it was simply eliminated. 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. 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.A typical AVD would be between 1 and 5, maybe a mximum of 10, to contain the IC noise floor under inaudible levels. But doing so would result in very low volume levels because of the missing audio pre-amplifier stage. 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. 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. 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. 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?

The above reasoning is supported by the fact that this model's sensitivity is on pair with similar radios of other brands, because doing a manual tuning or entering the RF frequency directly will acquire the RF signal without issues, while the ATS and the Auto Scan features fail to capture that RF signal. 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.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. If the MCU firmware is shuting down theCS4863 to avoid these nasty noises during band switching and fetching memory preset stations, as it should, then probably would be possible to fix it by following the Texas InstrumentsLM4863 datasheet. 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.

Confirmed. Litz wire speccification used in the single coil around the magnetic ferrite rodantenna is optimized for MW frequency spectrum. An additional LW coil with adequate Litz wire would be required, as seen in the good old radios of yesterday. 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. Even when inserting a fully charged Li-Ion battery, the radio only shows 3 bars (corresponding to at least 4.1 Volt reading)for a few minutes of usage.After that it will show 2 bars (around 3.7 Volt reading) for many hours of usage.Eventually it will show just 1 bar (low 3.4 Volt reading).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. Due to product quality problems within 3-12 months of receiving the product,we can repair it for free, but the customer pays for the logistics costs incurred.