Warning: long story but could be useful!
So finally i was able to do a (not so optimal, very high wind/turbulence) range/performance test with the sunhans booster on the remote tx antenna. Note again: CE region!
It was a bad day to fly, my phone acted weird and had a disconnect for some reason, probably was playing too much with different flight modes and it got stuck/crashed. I could not see much either on my screen due to the sun, need
crystalsky..
Finally i ended up crashing the Creep while flying in a forest, not related to testing. My own screw-up. No sig damage though, the Creep still flies.
So. Back to the booster and range:
In my short carreer as drone-operator it seems success from the past does not guarantee more of it in the future. Phantom 3 seemed to benefit greatly from windsurfers and dbs mods. Ocusync seems tricky and near perfect though. From some internet research combined with own experience i can say for mavic in this region: windsurfers, nanosync, dbs...all bs. Do not buy. I hate it when producers lie about specs of their product but they need to make money so they do this.
In my case the dbs 02.2 mod was worse than stock and nanosync slightly better than dbs...
Now comes BOOSTING the tx signal: initially it looked promising. Mid range flying from the backyard in the middle of town i went out for about 2 km ( not further cause losing radio LoS) With booster full bars on rc, without booster it's half of that so it is good.
Today i went to the "hill" for an onubstructed low interference distance run (no battery mod). Had to be careful cause of very high wind not to run outta juice so had to limit my distance. I took off with the booster on, after 300 m i had 1 bar less, after 1 km total loss of rc initiating RTH!!! WTF?!
So recap the mod: nanosync mod with the left antenna boosted by 3w sunhans connected with custom size RG316 coax, booster fed by powerbank delivering 5v, 2.1amp. But...but.. it worked fine before, maybe because different (stock) cables and booster was powered by lower USB on tx?!
Tried different cable without booster: 1 bar rc drop after 1.5km, that was normal.
Plugged booster back in and connected different powerbank delivering 1 amp max...voila!! I do not know why but the stronger powerbank screwed up things.
So with the new setup i took the Creep out at 80m altitude to 5 km with 4-5 solid bars on rc and 3-4 bars on hd. Right overhead a town which i normally could not reach due total signal loss and auto RTH. Did not dare further because a bigger headwind component on the return. Im sure with calm wind/open water/ field it would give at least the FCC range if not limited by battery. Clearly the town's interference made me loose some signal but a very satisfactory outcome overall.
Conclusion: any compatible antenna will work as long as its boosted, don t buy the sales talk. For stronger HD the craft needs boosting onboard, less simple. Still looking into this but little playtime coming days. To make optimum use of the extended range battery mod is a must.
@CyberNate is doing an excellent job on this, thank you for that.