[Alex H.]

Please share the link where you got your cheap Revo/Sparky2.

Sure, I can, as I'm not affiliated with them or something. Looks like they are located in USA Florida, and the cheapest shipping to Germany is 8$.
It is a Revolution V2, but looks like a combination between revo and sparky2 but without the RFM module.

https://www.readytoflyquads.com/openpilot-cc3d-revolution-acro

[Alex H.]

If all you want is stabilized flight controls, they work fine. Great for quadcopters.

I want a flight controller that supports telemetry, GPS and OPLink, at least this is my target for actual drone.

[trust]

That's a great price for this board.
Looks like the OPLINK RF board is not attached, though there is a space to solder it (not easy).
Without that not sure how you connect an OPLINK.
Does it come with the 10 pin cable?
The mini REVOs I referenced have a dedicated connector for the OPLINKs - one advantage.

[TheOtherCliff]

TL;DR  If you intend to buy the RF parts and add them, you may as well buy a complete one.  On the other hand, if you need to swap the RF board for a different band (433MHz -> 868 or 915) anyway, then this seems like the way to go.

Now we need that enhancement to allow a Revo to act like a plain OpLink...

As a Revo class board but without telemetry it is a good price, especially if you buy multiples, but it looks like the RF connector, cables, antenna are missing too.  Probably the rest of the back-side components (for RFM22B) are there if you want to build it out.  Servo pins appear to be free if you want them.

eBay used to be a good place to buy things like RFM22B, but they want like $18+ (none from china) for them now!!!  Luckily aliexpress has them for $3.50 free shipping if you are willing to wait 2 months.  I don't know how long the Ali buyer protection is.  It may be a scam.  On eBay lately, if shipping says it will take more than 1.5 months, then don't order it because it probably won't arrive and they hope you will forget by then.

If you want to build it out, it is still about 18+8+4+5= $35 for 1 (without cables or antenna).  Much better price for 2+.  About (36+8+7+7)/2= $29 each for 2.

[Alex H.]

Some mistakes have been made that day when I bought that board. I bought also a minimOSD 8$. As about the cables, now that it is talked about I wasn't thinking if the cables are included or not, only some options about S.H. and PIN heads were provided on rtf site. I have forgot about the pin heads, but I have some at home, this will not be a problem. Cables I still have some at home, possible the S.H. 10 pins connector also.

The remaining part will be the antenna connector on the board and the sma antenna adapter cable...

The board is advertised as naked for slim Fc profile... I don't even know that should mean, when there are so many cables hanging from the board.

I have found on aliexpress rfm22b boards with 4,2€, I have bought 4 of them with shipping was 21,15€.

I am still bellow 64€, as this one is asking on amazon:
Hobby King OpenPilot Revolution (Revo) 32bit F4 Based Flight Controller w/Integrated 433Mhz OPLink https://amzn.eu/d/dAYCsgG

[Alex H.]

I will need help to identify the RF connector that should be on the board.

Looks like a MCX, as MMCX is too small.

[TheOtherCliff]

MMCX.

[Alex H.]

Just received my rfm22b, minimOSD(not in the picture) and Revolution V2.
Now I'm missing a OPLINK mini.
Wrong cable adaptor...

[trust]

Where did you get the minimOSD?