Speed is in relation to the recovery or reset speed. I base that on two items in the manual.
1. Under Capabilities and Limitations, Sweep Speed, it says: "The F70 is noted for it's quick response. It permits the user to sweep the searchcoil quickly in order to cover more gorund with very little risk of losing targets. In general, if you are searching an area where the desirable targets are more than 8 to 10 inches deep, a faster sweep speed will detect to a greater depth and yield more accurate target ID's."
2. Under both the Discrimination Mode (pg 13) and Autotune Mode (pg 12) it says Speed: "There are two speed selections, DEFAULT and SLOW. dE = default SL=slow Slow speed provides more depth detection on more highly conductive metals. SL is more likely to result in noisy detector operation".
If the first statement tells us that a faster sweep speed is recommended for greater depth, and the second statement tells us SL provides more depth, then SL must not represent sweep speed. It seems that it must be reset speed. JMHO HH Randy