The IC-E90 is a tri-band FM handy designed to operate in the 6m, 2m and 70cm amateur bands. For some while there has been interest in a modification which would allow these sets to work in the 4m band too.
A modification published on-line a couple of years ago merely described how to remove the out-of-band inhibit function, so allowing the set to transmit and receive at 70MHz. This took no account of spurious outputs from the transmitter, and one correspondent had interference problems reported by local military air traffic control!
Happily, one of the major UK dealers can now supply these sets ready-modified for 4m use with the inclusion of a filter to reduce spurious outputs, although they can only achieve a second-harmonic suppression of around 33dB, so it is not advisable to use the rig into a external antenna or amplifier without additional external filtering.