Yes.... RG-6 loses 6.1 dB per 100' at 870 MHz. If he reads + 15 dBmV at the tap and has 100' drop, he should know that he has 15 - 6.1= 8.9 dBmV
This is the base of CATV and every should know what loss is.....
Joe 50
This is CABL.com posting #192554. Tiny Link: cabl.co/mYfS