CHIRP

I looked at id880h.py (my first ever look at any Python code), and while the "get" part of the code looks easy to change, the "set" part references "chirp_common.is_fractional_step(...)", so unless that reference is removed, the change looks a bit more complicated. Presumably the radio's logic in selecting a multiplier is to try them in descending order, picking the first one that doesn't give a fractional result. I presume this only because 121.5 could have used the "5000" multiplier, but instead the radio picked "9000".

I'm hesitant to change the architecture by suggesting a change that removes "chirp_common.is_fractional_step(...)".

I think you are confusing the "step" (which the user can set), with the internal "multiplier" that the radio chooses when storing a frequency.

You don't have to use the same algorithm that the radio uses (my statement in my 1st update as to what the radio does, is only a guess), you (again, my guess, but it works in my code in DStarCom) just have to use a multiplier that gives the correct (exact) frequency (and of course store the corresponding multiplier index).

Eg, for 121.5, I think you could pick 5000, 6250, or 9000 as the divisor (since all divide evenly into 121.5x10^6), and store "0", "1", or "4" for the corresponding multiplier, and I think it would work. 8333 won't work, as you point out.

In the example, the radio picked a multiplier of 9000, and stored 13500 (decimal) and a multiplier index of 4. Your code just looked at the low-order bit of the 3-bit field, interpreted that as "0" (not "4"), multiplied by 5000 (not 9000), and arrived at 67.5MHz.