Mike,
First let me tell you that I'm a newbie to ham radio, having earned my technician and general licenses in March of 2020. Bear this fact in mind as you read my comments.
I don't know about R63, there was a change made to R83 from 10 ohms to 2.2. ohms between v3 and v6. As far as audio level is concerned,?I determined that the Baofeng microphone that was shipped with the uBITX was worthless and replaced it with a CB microphone with?a built-in preamplifier (thanks to Evan's post). That improved things some. Then, I lifted one end of R86 and put a 33 uH inductor in series with it and I added 220 pF capacitors across R87 & R88. These changes really improved the power output on the 40 meter and 20 meter bands. (All of these modifications came from posts on the BIT20 group. I refer to them as "Howard's modifications.") In fact, I've made QSO's on both bands now after stringing up an EFHW antenna cut for 40 meters in the backyard.
I recommend that you have two important pieces of test equipment - a nanoVNA and a watt meter. I use the nanoVNA to check the VSWR of any antennas I try out. The power meter will help you evaluate the effectiveness of any changes you make. I'm not a big spender, so I bought the nanoVNA for about $100 on line and also found instructions to build a power meter. The screen on the nanoVNA I bought is small, BUT there's a free download that will let you display data on your laptop or PC and print it out to document your progress. I have no idea about how accurate my "poor boy's" watt meter is BUT I can make meaningful "before" and "after" modification comparisons ... and I can highly recommend "Howard's modification" to you. It doesn't come on the v6.
There are posts that discuss other modifications to the v6 that will improve power output on the higher frequencies at the expense of the lower frequencies. Right now, I am not ready to make that trade off.
One other very useful improvement that you will eventually want to make is installing Reed's software on the Arduino in your v6. I knew nothing about Arduinos and I was able to do it, so it isn't hard to do. Reed's software greatly improves the user friendliness of the v6. Among other things, it allows you to store 4 different favorite frequencies.
Rather that make this message any longer, I am going to stop now. If you want to know more about any of these topics, I will be happy to correspond with you on this board or on "the side" directly. Let me warn you though, there are a lot of folks in this group who know a lot more about the uBITX than I do. Most of my information comes second and third hand from them, and my "Elmer" whose real name is Bob.
73s
Stephen, KO4CVU
