No way to check, if the antenna connection is not doing what it is supposed to (bad connection, bad antenna, inappropriate antenna) then it will blow. You will know if it happens because you will go half as far as you usually go (if you're lucky) and have a failsafe and fall out of the air, plus RSSI will be complaining almost immediately.
It doesn't really have a 5dbi mod, what it really has is an RP-SMA (not SMA, be careful here) connector installed stock. It becomes "5dbi Modded" when you plug on a 5dbi antenna to this RP-SMA connector. But I know what you mean.
It comes with a 2dbi, that keeps it within FCC/Ametuer Radio specs, as soon as you plug on the 5dbi you make it illegal, but many do it anyway. I get plenty far with a stock antenna and consider an unneeded and very real risk
Yes the TX is replaceable
Here is a little blurb below about it from RCGroups, and I have been working with radio wave propagation and similar things in my career all my life, I know every bit of it to be true. Not wanting to sound like the RF Police, just want you to remember that with antenna propagation, you don't get something for free. When you up your dbi, it doesn't do anything for the signal that it also doesn't do to the noise floor, plus you radically change the radiation envelope (think the shape and size of the donut coming off your antenna) so you get further in the exact middle of your propagation envelope, but the edges shrink significantly for that gain in the middle. Think of it like the difference between a floodlight and a spot light, the floodlight gives you pretty good light in a large area, and a spotlight give you even brighter light in the spot but much less outside that spot. I know people who have blown their transmitter and just added a XJT module to the Taranis in the back bay, or use the stock antenna and rarely take it off to keep from wearing out the RP-SMA connector or run the risk of forgetting to attach before powering on.
It can really be a great RC, just know what you are dealing with so you can make the right call if and when you decide you need the 5dbi for something, even if you do have your HAM Technicians license.
IMHO
FROM RCGroups
Taranis Plus Special Edition TECH TEARDOWN - RC Groups
A WORD ON ANTENNA MODS, TRANSMITTER SAFETY AND YOUR RC AMATEUR RADIO TRANSMITTER
I personally am not a big fan of the SMA Antenna Mod; I see it as an unnecessary point of failure. SMA Connectors are fragile, and they are made for few (100-500 or so, depending on the quality of the connector you use) mating cycles. Joshua Bardwell
lost a week of flying because he thought he had fried his Taranis; but on the other hand,
he bought a Taranis Plus SE to replace his because he still likes the idea of the 5dBi antenna.
I find the big bulky thing a total PITA, myself.
For most users, the SMA antenna Mod is an invitation to do stupid stuff like experiment with every POS "WiFi Booster" antenna they find on fleaBay, and MOST users doing the mod do NOT hold a valid Amateur Radio License of ANY KIND, so simply screwing on a different antenna is ILLEGAL anyways.
Most users playing with this stuff don't know the difference between SMA and RP-SMA (Which the Taranis SE PLus uses) connectors, nor do they know that if you don't use the right one you can FRY your Taranis' RF board and KILL it.
The Taranis is FCC Certified as a "License-Free Amateur Radio Transmitter"; this license applies to the the ENTIRE assembly, including the stock antenna, to which the radio is certified. That means the soldered-on stock antenna in the case of most Taranii, and that means the supplied 2dBi screw-on antenna in the case of the Taranis Plus SE.
Simply screwing on a DIFFERENT antenna VOIDS that certification.
This is illegal in most localities unless you hold a Technician-class Amateur Radio License or equivalent, and for good reason. If you do this without knowing that your antenna assembly, including the feed cable, is tuned properly to the transmitter, you can damage your gear or cause your TX to transmit a distorted signal, which definitely CAN interfere with your flying buddies' signal or your neighbors' WiFi or TV.
If your antenna assembly is NOT tuned to your transmitter, odds are you are actually producing a WEAKER, more distorted signal. With microwaves, bigger is NOT better... in fact, it usually means "Out of tune". There's a reason they're called MICRO-waves.
"Oh, I've been flying my 5dBi antenna for years, and I've never interfered with anybody else's radio... you're way exaggerating!"
Really? HOW WOULD YOU KNOW?!? Do you have magical Radio Eyes that can SEE microwaves bouncing about? Do you perform a spectrum analysis and record logs of its output EVERY TIME YOU FLY with your illegally modified transmitter, then review those logs afterwards?
Of course you don't... just like most folks don't hold even a Technician Class Amateur Radio Operator's License or equivalent. The kind of interference we're talking about here is usually only for a few moments... not enough to cause you to lose control for any extended period like in the bad old days of 72MHz, but definitely long enough to make you zig when you should have zagged, and before you know it you've crashed your 50MPH quadcopter and don't even know what really happened. So you chalk it up to a random glitch.
But the thing is... YOU ARE THE GLITCH. And you are the glitch in your flying buddies' crashes too; just as they are probably the glitch in YOUR crash with their own modded antennas.