I'm sure that non-US versions of this radio have slight differences that will affect the operation of these features. For example, I've read that certain versions require that a jumper be physically cut inside the radio in order to enable the cross-band repeat feature. This is not true for the US version of the radio. This document covers the US version of the radio, which is what I have, though I will add additional information as it is submitted to me. My email address is listed below and I welcome contributions.
I've read that resetting the radio is required at this point, to cause the radio to notice the newly-installed board. I can't say if it was necessary or not. It was easy enough for me to dump my configuration to my PC, reset the radio, and reload. There is no obvious indication on the radio that the new board is installed.
Remote control DTMF sequences are now listened for by the radio on the sub-band for control of the MAIN band.
Before general commands are accepted, you need to 'log in' from the remote radio. These are the sequences used to log in and out:
B<code># -- log in (& cross-band repeat off)
DB* -- log out & enable cross-band repeat
B* -- log out (leaving cross-band repeat disabled)
The code that is used to log in is the 3-digit password set on the DTMF memory screen, which is accessed by holding the DTMF button on the radio for 2 seconds. This option does not show up on radios without the UT-49 option installed.
While the IC-2800H is logged in, it is possible to control the MAIN band with the following keys:
1 -- Select call channel
2 -- Select Memory mode
3 -- Select VFO mode
6 -- select high power
9 -- select low power
More generally, the following keys can be used as their equivalent on the radio:
A -- Clear (CLR)
D -- Enter (ENT)
* -- Down
# -- Up
Down and Up keys function as the down and up keys on the HM-98, dependant on the mode (Call/VFO/MR) the radio is in. Holding down the Up or Down buttons has no added effect -- only one up or down step is taken. Enter can be used to enter a frequency or memory channel directly, also dependant on the current mode.