Hi,
are there any small receivers that are compatible with Futaba 3pv (I´m using a R203GF-reveiver now)?
There are some on ebay and banggood, but which ones will work?

There are some micro FHSS receivers for 1/24 and smaller scales, they also have snaller connectors for the servo/esc.

https://nl.banggood.com/DasMikro-FUT...SABEgIg6_D_BwE

You can run the R204gfe-e. It’s a good amount smaller than your r 203gf.

Not really, its about the same footprint.

DasMikro branded Rx's are legit, I have not used them for Futaba, but I have used them for both KO Propo and Sanwa radios flawlessly, they produce slightly slower frame rates because they use lower quality components (roughly 15ms using my PCM tool), but the slowness is undetectable and did not degrade my fast lap time nor consistency.

Thats interesting, but it uses JST(?) connectors? Do you use a adapter on those connectors?
What kind of case do you use to that receiver?

I have used these on my 1/24 car, similar to a MiniZ but they called it a Mini-Q3, the JST wires are included, you can crimp your own adapter or simply splice solder. I did not use a case, I covered with shrink tubing and glued it to the chassis with

E6000

E6000

You Tube

On my search for small receivers, I came across the FRSky. Haven't tried it yet myself, but I heard good things about it. There are some models compatible with futaba, for example the TFR4B. Very small, seen it on some electronic setups pictures at Petit RC.

https://www.frsky-rc.com/product/tfr4b/