QO-100 and WLAN / Wi-Fi amplifiers

The EB-AB003 2.4GHz linear amplifier seems to come in two versions. A later one sold by Passion Radio has the external model number EB-AB003 but the internal marking HS2405X2 V.0.1.

The mod is for permanent TX (as this is just a dumb linear amplifier) - to disable its “VOX” or RF detection capability.

The “classic” EB-AB003 is laid out quite differently to the internals of this later version. However the chip is the same and the fundamental pin bridging modification is the same as described here: https://www.george-smart.co.uk/2019/03/limesdr-edup-pa/

I found some photos from OK1UM here outlining the mod for this version. I have not yet done the mod, but I wanted to get it captured for future reference.

It appears to consist of:

• Connecting the RF input to a different point on the board
• Possibly cutting tracks
• Bridging together pins 4 and 5 of the ADA4851-4 chip.

The first two parts are probably just to reduce attenuation. The third part is the same as the old version.

Note that the RF out port is a reverse polarity SMA socket!!

The F1OPA 2.4GHz 100mW amplifier is ideal for driving this power amplifier.