// CQDX.ru

TL-SDR has just launched the RTL-SDR Blog V4 dongle for software-defined radio (SDR) enthusiasts based on the Rafael R828D tuner chip with three switchable inputs instead of the R860 chip used in RTL-DSR Blog V3 dongle.

The new model still features the Realtek RTL2832U demodulator found in all previous versions of the SDR USB dongles but adds basic input filtering, integrates an improved LDO for the power circuity leading to fewer heat emissions, and improves HF reception thanks to a built-in upconverter.

The main RTL-SDR Blog V4 dongle improvements include:

• Improved HF Reception thanks to a built-in upconverter instead of using a direct sampling circuit. Some positive consequences are that there’s no more Nyquist folding of signals around 14.4 MHz, improved sensitivity, and adjustable gain on HF.
• Improved filtering thanks to the three inputs of the R828D tuner chip found in the V4 dongle. Three bands (HF, VHF, and UHF) are captured through the SMA connector with some isolation between the bands and less risk of interference from broadcast stations.
• Improved Filtering is made possible through the open drain pin on the R828D tuner which connects to notch filters for common interference bands such as broadcast AM, broadcast FM, and the DAB bands.
• Improved phase noise on strong signals and less heat thanks to the improved power supply design with less noise and low consumption.
• Various minor changes such as a new bias tee LED and a small cutout hole in the enclosure to more easily tell when the bias tee is on.

The R828D chip used to be quite more expensive than the R860 chip, but the price for the latter has significantly increased since the beginning of the year, and the R828D-based V4 dongle now ends up being cheaper than the V3 model. But the latter is not going anywhere because the new dongle does have some disadvantages as well:

• Average of 2-3 dB less sensitivity on some bands due to the increased filtering
• The new dongle does not work with default drivers and requires the RTL-SDR Blog drivers.
• The R828D tuner chip is not produced anymore, so the V4 dongle should be considered a “limited edition” as production will stop once the chip can’t be sourced anymore.

The RTL-SDR Blog V4 dongle sells for $29.95 on Aliexpress or $39.95 with an antenna set including free shipping to most countries and should become available on Amazon within the next two months. You’ll find more information about the new USB SDR dongle in the announcement.

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