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). 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. 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. 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.

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. 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. 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.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. The design choice used on the D-808 was to save costs on the audio pre-amp and simply configured theCS4863's OpAmp1A andOpAmp2A with a very high bridged mode differential gain of 77 (!)

Here are some of the behaviors detected by several owners and testers since this model was released:​ 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.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. 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. 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. 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. Power supply issues - Power ON key fails to turn the radio ON, or else it power Off by itself, even with a fully charged battery, several causes for this, one being the use of inappropriate batteries (physically incompatible with the battery holder terminals).

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. 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. Confirmed empirically, by listening to some radio stations at night. This radio is kind of silent below 2.5MHz.My 2021 unit came with 3.81V in the battery (still a XHDATA 2000mAh device) and the battery level indicator had 2 bars. 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.