for the hackers out there:
The Quansheng UV-K6 – A game changer for Radio Direction Finding? (Wide range RSSI meter). – YouTube
https://www.youtube.com/watch?v=h8llT_5MrHE
a two way radio with a signal strength readout of +7 to -120?? dbm
or
DW-400 RF Field Analyzer – Good for Radio Direction Finding? – YouTube
https://www.youtube.com/watch?v=Pmii34mDVF4
a tunable RF field analyzer that reads from 0 to -126 dbm
0 dbm being 1 milli watt and -126 dbm being about the max sensitivity of a good VHF radio.
Note: these may max out before you get within 50 foot of the fox, so you still need a sniffer.