Re: the "slide-switch mod", I think the question refers specifically to the Yaesu FT-757GXII, which has such a switch. This is a ham radio, not a marine radio. As such, it can be modified in any way the user likes, including digging into the circuitry, when used on the ham bands by a duly licensed amateur radio operator.
In ham radio, it's the licensed ham who is responsible for ensuring that his emissions are "clean" and within the alloted spectrum space. Other hams help "police" this, and will not be hesitant at all to tell you if you have a bad signal or if you're operating out of band, splattering, etc.
FCC certification for ham radios isn't the same as for marine radios. It's just for the import and/or sale of commercially marketed equipment. What the user chooses to do with the radio after sale is up to him/her, since the responsibility for proper operation rests with the licensed operator who, by virtue of his/her licensure, is presumed to have enough knowledge and technical knowhow to ensure clean operation. Hams can and do build their own radios, both from kits and from scratch, using their own designs or those of others. This has always been and continues to be perfectly legal.
With similarity to the physician's credo, "first, do no harm" is the ham's credo: "first, cause no harmful interference".
Not so with marine radio, land-mobile, aircraft, military, etc. These radios can only be worked on by a technician with a commercial license (GROL or better), and cannot be modified in any way without voiding the certification.
Bottom line: the Yaesu slide-switch in a ham radio was a good idea; too bad other ham radio designs didn't incorporate it. The result is the need to hunt for instructions, evaluate their origins, snip diodes, change dip switch settings, reboot the microprocessor and re-enter all stored contents, etc., etc., sometimes in circuits which are impossibly small to deal with, physically.
Why modify a ham radio? Several reasons: to access the new 60 meter channels (5 mHz); access the WARC bands (older ham radios didn't have these); access MARS and CAP frequencies; allow for operation in an extreme emergency on marine bands, etc., etc.
At least that's the theory. Practice, of course, differs depending on circumstances. YMMV :-)
Last edited by btrayfors; 01-18-2011 at 07:00 PM.