re: the very narrow range that the DT502 will respond to the remote.
As previously noted, I am amazed at how terrible the DT502 is with regard to the need to carefully align the remote to the unit in order to get it to respond.
A quick inspection of the remote shows a possible cause -- the LED is shrouded deeply inside the unit. Other remotes that are well designed take care to un-shroud the LED, but still protect it, in order to provide the maximum range of angular effect -- thus not requiring the user to take pains with 'aiming' it.
Not sure if the forum will let a first time poster put up photos, but if it will, I'll provide examples of the original and an RCA unit.
Anyway, I saw that there is a ring around the LED, and if that ring were not there, it might provide a wider range of operation. Of course, the LED itself, the intensity of the device, the receiver design also are big factors as well, so I was not overly optimistic.
Not seeing any obvious way to disassemble the unit (no screws) I gently worked a scalpel around the diameter of the shroud, until I felt it cut through. At that point I used a screwdriver, thinking it might break off cleanly on the scribe, but this is that softer plastic, so it just bent and mashed around. Eventually, I used a pair of diagonal side cutting pliers to finish the job, leaving a nice neat circle relieving the LED. During this operation, the top and bottom halves partially separated, but not knowing if they were glued, or tabbed, and if I could get it back together, I did not take it all the way apart. It snapped bac together with no problem.
When I tested the modification, unfortunately, the unit is STILL highly directional, and is no where near as nice as any other remote I have. That said, it does appear to be significantly less sensitive (more likely to work at off angles), so I'm glad I did it. Only you can decide if the mod is worth the danger of breaking you remote, but it was driving me insane, so I had to do something, even if imperfect.
RCA for comparison: