Welcome to RR. PL tones have no direct affect on the frequency. What they do is block all other users with a different tone from being received. Quite often, there will be more than one agency in your area using the same frequency, usually with different PL's. You should try the frequencies without any pl 1st to see if there is any interference from another agency. Another use of PL's is to limit adjacent channel interference. Often, there will be users with frequencies very close to the one's you wish to hear. Using your agency's PL will usually prevent bleed-over. You can find most PL's here: http://www.radioreference.com/apps/db/?ctid=2286 If CSQ is listed under tone, it means they do not use any tones at all. 151.34 uses 606 DPL, which is different from a PL, but all scanners that can program PL, can also select DPL.
