I think I might be on to something here.
Scuffs, you can break the 89 channel limit. I don't have analog cable so here is an atsc tuner export for one of my atsc cards:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Media Center\Service\Video\Tuners\{71985F48-1CA1-11D3-9CC8-00C04F7971E0}\{208AD2F7-0ECE-43AA-B147-B5C226BD61A5}\TuneRequest\Tuning Space]
@="{A2E30750-6C3D-11D3-B653-00C04F79498E}"
"Name"="ATSC"
"Description"="Local ATSC Digital Antenna"
"Network Type"="{0DAD2FDD-5FD7-11D3-8F50-00C04F7971E2}"
"MinChannel"=dword:00000001
"MaxChannel"=dword:00000063 <--- channel 99
"InputType"=dword:00000000
"CountryCode"=dword:00000000
"Min Minor Channel"=dword:00000000
"Max Minor Channel"=dword:000003e7
"Min Physical Channel"=dword:00000002
"Max Physical Channel"=dword:00000045 <----- Channel 69
I didn't test this, just an export. I also found a channel override file in the ehome directory where you can break out and specify each channel with frequency. The red seems to be where all the digital tuners are put. And like your previous findings, I am seeing every card and every tuner I ever installed in the registry. only the 4 currently active are enabled. The rest are there, including the analog side to hybrid tuners.
EDITED TO REMOVE MY REQUEST FOR TESTS AND PUT OUT A WARNING Max channel is the highest channel number thats the frequency is on "file". Do not change max channel and only raise physical channel up to max channel unless your tuning with an stb, then its safe to change around more but really no reason too.
After I've had some sleep and get to work, I'll have time to post a quick howto for changing around the input type (seen above) to change the frequency chart your using and work up a list of safe maxchannel settings per chart type. (and a howto to override the chart and make your own custom one). Like say a frequency chart for hmmm radio?? add missing channels to the guide, never get picture but record the sound at a low encoding setting? Oh I did figure out the encoder settings. I may start a series of threads on these things. just posting this to help out scuffs with whatever he is trying to accomplish. don't get your hopes up too high for radio, that ones going to be a little hard to figure out. digital radio might be easy though!
Bryan Socha
Media Center MVP