Identify RF transistor, UHF antenna distributor

[Vicus]

Hi, I need some help in identify this transistor. I desoldered (and yes ripped up a pad) to test it. 42M is the mark on the top of it. It's a 4 pin sot with the top left wider. The bottom right and the upper left pad are gnd. I think that it's fried because I measure 12ohm from what appear to me like the collector and the emitter. Of course I have ho signal on the output. The product is a "T bone free solo antenna distributor". It sould buffer or slightly amplify an antenna input and distribute it on 4 output. 5V from a 7805 is the psu.
I can't find any possible transistor, the package also seem unusual.
Thanks.

PS the picture is upside down. I don't know why it rotate during upload.

[shakalnokturn]

Package could be a variant of SOT-143.

I haven't searched with marking codes.
Try searching Taobao with sot-143 (b/r) and 42M see if that comes up with any UHF/wideband BJT's.

Edit: The NXP BFR and BFG are the first examples that come to mind.

[Vicus]

I do identify this:
https://www.tme.eu/Document/4af7f3725e1f0dabe5f62a4ed081108d/BFU630F.pdf
but I really don't know how rf transistor work. Does the base doesn't need a bias current like standard bjt transistor?

[TheMG]

It could very well be an integrated RF amplifier, not just a simple transistor. It would have the required biasing circuitry internally, and only need to be supplied DC power decoupled from the RF output, and that appears to be what's happening here (unless there's more going on outside the picture, can't see where that DC trace is going, does it go direct to the power supply or are there some biasing resistors in series?).

Unfortunately I haven't had any luck with that SMD marking.

But yes, an RF transistor would need proper biasing to operate in the linear region.

[Vicus]

It goes straingt to the 7805.
So it could be this one:
https://www.infineon.com/dgdl/Infineon-BGA427-DS-v01_01-en.pdf?fileId=db3a304314dca3890115418dca4d1638

[Vicus]

This one seems bettere but still not exactly the same.
I have to measure the R bias.

[Vicus]

Ho R bias in the PCB. I'll try with this one:
https://www.mouser.it/datasheet/2/412/SPF5043Z_Data_Sheet-1500773.pdf

[Vicus]

The oem degner replay of my email. They say it's an Agilent MGA-53543 and of course il discontinued. So I did order some Qorvo SFP-5043 and they works fine.