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

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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. 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.

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.Confirmed empirically, by listening to some radio stations at night. This radio is kind of silent below 2.5MHz. 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.

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. The DC-DC converter was not properly shielded in the previous versions, being a source of RF noise. Other better radio brands, even ones using the same basic chassis, use shielded DC-DC converters. 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.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. The battery was charged using the radio integrated battery management and supplied microUSB cable conected to a 5V/2A smartphone poweradapter. 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.

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. 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.Allegedly, the Auto Tuning and Store feature seems to only find the stronger RF signals, probably because the firmware was set to use a too high threshold detection level, and there is no user setup to change it.The same behavior happens for the Manual Scanfeature, by presssing and holding the Up or Down keys for 2 seconds. 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. 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. 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.