I started putting together my uBitx (v4) months ago. I added a better volume pot, CEC firmware, a Nextion display, and an AGC board. I put it in one those blue metal cases from Amazon stole some knobs of an old stereo, and pretty much let it sit while I wasted too much time reading about mods, and worrying about feedlines and antennas. But within the past week I realized that this is not my burly TS-430S, and it probably won't start an RF fire on my wall behind the tuner, so I decided to say "to heck with it" and just start flogging the uBitx.
With the exception of using an MFJ-971 antenna tuner, I went full "bull in a china shop" and did all of the following things "wrong":
1. Antenna is an unknown length (maybe 100ft) of 28awg enameled wire going East - West at about 7-8 feet above ground, surrounded by houses and trees. It is "counterpoised" by a 50ft (who knows how much is connected) rain gutter going North - South. The ends of these are fed entirely without care through a wood block in the window frame into the back of the tuner.
2. Hooked up audio cables direct to the ins and outs on my computer with zero isolation. Had to adapt the mic end to avoid setting off the PTT, so I stripped off an old plug, soldered a couple wires to it and hooked those with clip leads to the plug on my 1/8 patch cord. I did have to ditch that USB extension cord I was using for CAT though, because it was noisy. Just went to the cord box and dug up a longer single cable to go from Raduino to Computer.
3. No ferrite beads, strapping, bonding, or other fiddly stuff was used in or out.
4. The Nextion is only using 2.8 of the 3.2 inches and I don't notice it.
5. The AGC board doesn't seem to do much and is probably wired wrong. Don't care enough to go look for updated docs yet. Low audio? See #2 above -- I hooked it to the computer and listen through my headphones or speakers from there.
6. On some bands I can't tune much less than 3:1 and on most the tuner only says I'm putting 1/2 a watt forward. Could be misreading (me or it), but I'm too lazy to rig up a dummy load and put the oscilloscope on it. I leave it on "TUNE" (from WSJT-X) way too long trying to figure it out, and sometimes the back of the case gets warm. Sometimes I've run it with the SWR meter almost pegged with the fanciful thought that it might be lying.
And so how did all my carelessness punish me? With a ton of fun and true amazement at what such a shoddy, minimal setup can do, using our favorite modern mode, FT8 of course. With WSJT-X (ok, properly configured) and pskreporter.info, I have spent hours that I can't afford to waste (could be playing Fortnite!) making contacts from U.S coast to coast, and from Alaska to Mexico, and being heard from New Zealand, Japan, Europe and South America. I'm in Washington State, by the way. And I'm operating with this fabulous antenna on 15, 17, 20, 30, 40, 60 (yes 60), and 80 meters. Hard to tell if anything works on 10 meters these days. But those times I mentioned when I run at an impossible SWR level, I can still get signal out (ok not always).
So the message is that it is quite possible, with a just stock uBitx (I didn't really need more than CEC firmware), to enjoy the absolute wonder of wafting intelligible messages across the globe on the tiniest amounts of RF. And as for the spurs / etc., I'm sure the FCC will come for me, right after they get Billy Crowell and my neighbor's grow lights.