====== Amplifiers ======

===== AB-IOT-868 =====

An 868 MHz band amplifier from Aliexpress.
Marked AB-IOT-868.

[[https://www.aliexpress.com/item/1005006756311325.html]]

===== From the listing =====

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.

===== Testing =====

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.