For microwave transverter use it is sometimes useful to have extended receive 2m coverage from 143.5 to 148.5Mhz with step sizes of 10 and 5khz. The article here describes what to do, but the pictures below show the way around the rig to make these mods. (Note:- It is illegal to transmit outside the 144-146Mhz range, thus this mod is best used for receiving only!) Note too that these mods apply only to the early Mark 1 FT290R, with the central tuning knob, not to the later Mark 2 version.
You'll need to remove the battery box (loosen two side screws, plus remove the two bottom screws) and then locate the vertical PCB which has the fuse and the standby battery on it. This will withdraw upwards (no need to disconnect anything) and when you have done so you will see the 4 links on the PCB behind it.
The link sketch below shows the PCB tracks as they are presented to you when you have the bottom off the rig and the battery box removed. The dotted lines show the links I have in position to give me the 143.5 to 148.5Mhz coverage, i.e. three links soldered in and one omitted and that position left open circuit. I would suggest that all power be removed from the rig before soldering begins and that a well grounded fine tipped soldering iron is used for the job, so as not to incur static damage. Its fiddlly but with a fine iron you can do it.