To clear up confusion between weighting and ratio, they are not the same thing. The RATIO of a dit to dah is always 3, as it should be, otherwise if a dah is shorter than this (it can be of course!) then CW becomes difficult to read, although making a dah longer than this (as is usually the case — deliberately — when using a bug key) the intelligibility of the CW is not worsened, except for those who are used to listening mainly to "perfect" CW. With that out the way, know that your keyer will be having a ratio of 1:3 for dits and dahs and most keyers probably don't have any setting to chance this, there is not need to invent a "new" Morse.
Weighting on the other hand, is required because although your CW sent from a paddle listening to the local side tone may sound just fine, in actual fact, particularly older rigs but even modern ones, there is a delay between the circuit being closed by the key and the rig switching from receive to transmit. Slower relays etc, will result therefore in each dit and dah on full break-in, or the first part of a dit or dah on semi break in, being cut short. Therefore the CW going out on air will sound "clipped" — BOTH dits AND dahs will be too short. The effect is shorter dits, shorter dahs, and longer gaps in between, so the CW will not sound nice, and again, not be so easy to read.
To get around this, keyers have "weighting". I'm not sure if they ALL measure this the same way, but for the keyer I have the deafault weighting is 5% — this means the length of EVERY DIT AND DAH is lengthened by 5%, to COMPENSATE for the time it takes to change the rig between RX and TX, and thus the resuling sound on the other end of the QSO is just as you (would) hear it on your side tone. In actual fact, you'll probably hear it 5% longer on your side tone, certainly on cheaper models like I have, but it's still easy to understand here, while also making it fine ON AIR. Normally you won't need to touch weighting from the default setting on your keyer, but, ask for feedback from your QSO partners (experienced CW operators) on the air, ask them if your dits or dahs sound clipped, too short or too long. You need to ask an experienced OP though, as many will misunderstand this question and not know what they are really listening out for.
I had a great many QSO before an experienced OP (I believe it was VK2ARZ) told me my CW was clipped, no one else reported it. This was on a different rig that had slower RX-TX and I had to compensate for it by increasing weighting. If you put too much weighting though the dits and dahs will still have the SAME 3:1 ratio — but they will both be too long, with the spaces between each dit and dah being too little, again making for difficult to copy CW. I suppose that if you keep increasing the weigthing too much you could arrive at a situation where there are no gaps between the dits and dahs and all you'rge getting out is a continuous dahhhhhh!
So weighting is not about "what sounds good to you" or about your own preference, it is about ensuring that the Morse being sent ON AIR is the actual CW intended, and not clipped short. Hope I've got all that right and understandable. If you search the web for more information you'll probably find the same explanation and probably a lot shorter than I've done.
