Club Log's database is an interesting source of SCP information for general purposes. It may not suit specific contests as it is purely based on DX logs. The SCP file contains around 180K callsigns.
One of the purposes of this data is to enhance the log analysis features in Club Log itself, but the data is also freely available for other uses.
If you would like to try this SCP file, a weekly SCP update is generated as follows:
- All callsigns from current DXCC entities having more than 40 QSOs in the database within the last 3 years.
The SCP file is a plain text (.scp) file which is compatible with most contest software, or can be easily adapted. The file is available here:
https://cdn.clublog.org/clublog.scp.gz
The .gz suffix is for GNU ZIP. Most compression tools know what to do with this.