An 868 MHz band amplifier from Aliexpress. Marked AB-IOT-868.
Amplifier:
1. The product is a two-way amplified TDD working mode (that is, the transmit power and receiving sensitivity will be amplified equally);
2. The working voltage is 3.6V-6V;
Current requirement for power adapter(Not included) : Max. 0.72A
3. This product is highly professional, and wireless communication is greatly affected by the environment. We only guarantee that all parameters are measured by the instrument.
Bi-directional amplifier. Built in TX switch on signal, should be >=1dBm, but threshold is -2dBm. Alternative, switch with SW pin, high for TX. Remove resistor first. 850MHz-930MHz
LEDs: Green RX, Blue TX.
Operating Voltage ：AB-IOT-868-A： 5V（4.75V-5.25V）
Working current ： RX status ：10mA（±3mA） TX status ：≤720mA
Adjustable gain When the potentiometer is turned counterclockwise to the limit, the gain is 5dB； When the potentiometer is turned clockwise to the limit, the gain is 11dB.
I measured the gain at 869.075 MHz, on receive with 20dB attenuator, so -15dBm in, as 12.2dB. With 10dB atten. (-5dBm in), gain 12.4dB. 60dB atten, (-55dBm in), gain 12.7dB.
Tried with VNA output at -4dB, result with 60dB atten same within noise. Maybe 0.1dB less gain.
Didn't test on TX.