The SanDisk Ultra / Ultra 2 cards have proven time and time again to be the most reliable CompactFlash card to use with the Lo-tech ISA XT CF Adapter as well our other Lo-tech XT-IDE to CF adapter cards. These work best on the IBM 5150/5160. For best results, delete the existing partition and recreate it on the vintage machine you wish to use it on. Here is a bit more detail about CompactFlash card compatibility taken from our adapter listing:
Compact Flash cards are also not without their perils. Many cards we have found which claim ATA-2 compatibility are not fully compatible. This tends to be the case with lower end cards. We like SanDisk Ultra / Ultra 2. We generally use 2gb or 4gb cards, but larger or smaller can be used. Any ATA-2 compliant card should work, but be aware that some experimentation may be necessary. DOS 5.0 or 6.22 are probably best, as you can support a full 2GB FAT16 partition. Only use your target PC to format the card. Windows may, or may not configure the partitions correctly. Of course, you may run other operating systems as well, but create the partition via the OS setup. If for some reason your machine does not boot after FDISK and Format, run “FDISK/mbr” to reset the boot sector. This often fixes a hang at boot-time.
Please note that these are no longer manufactured so stock is limited. We will continually be on the lookout for more and restock as our inventory runs low.