ARINC recently updated its System Table of frequencies used by High-Freqency Data Link ground stations. The current table is number 49 (decimal). If you're using PC-HFDL, it should have switched to index numbers instead of the frequencies in kHz.
To get the kHz back, the user must either:
1. Listen to some squitters to make sure you have a good copy on the ground station. Wait for an aircraft to report that it is using version 48, which triggers an auto-update from the ground. As it receives the uplink data to the aircraft, clever PC-HFDL will write a new pchfdl.dat file over the existing one. I must be slipping - I didn't do this on September 4 when it changed, and now it's a little late for a ground station to be sending it.
2. Get a file called pchfdl.dat from someone who has done the update. Exit PC-HFDL. Go to your PC-HFDL directory*, change to the sub-folder called "configs," and copy in the new one from wherever. The old one is useless, so there's no tragedy if it gets lost. Even so, I tend to rename it and move it somewhere else first. Restart PC-HFDL, and if the numbers have switched to frequencies, you're there.
The pchfdl.dat file on this column's web site has been replaced. It works here. That doesn't always guarantee anything, but it's there. Again, the operative number is #49.
As always, the new frequencies aren't all that different from the old ones. The only visible change is the addition of three new frequencies for Johannesburg, South Africa. These, listed in ARINC's usual descending mode, are 17922, 11321, and 5529.
Good hunting!
*Most Windows 7-8 users make a radio directory outside of C:\Program Files, because otherwise older programs don't work right. Mine is C:\Radio\PC-HFDL. Even then, I had to mess around with it a bit to get the new pchfdl.dat to work. Most people, though, seem to have it work right the first time.