Copied from this thread:
https://www.vintage-radio.net/forum/...d.php?t=143847
I have a Compat C cartridge, the box and information sheet say "Stereo Compatible Mono Cartridges" and contain the following data:
"Compat X - Medium Output Crystal Cartridge, output 225mv, VTF 3-5g, load 1MΩ 100pF
Compat X2 - High Output Crystal Cartridge, output 525mv, VTF 6-9g, load 1MΩ 100pF
Compat C - Medium Output Ceramic Cartridge, output 170mv, VTF 5-6g, load 1MΩ 100pF
Electronic Reproducers (Components) Ltd. Hedley Road, St. Albans, Herts."
These cartridges were also boxed and sold by Goldring.