Do I need the CTCSS Hz field filled?

[Fsher21]

I have a radioshack 20-197 digital trunking scanner, and I got most of it figured out. The thing that seems to be my only problem relates to the CTCSS Hz field. If I have it populated with the information off this site, I can hear the radio chatter. For all the other frequencies I entered, i just set the sq mode to CTCSS and the CTCSS Hz field to "search". I do not appear to be hearing anything from those with just the "search" in that field. How do I find that tone so I can hear the frequency I have set, or should I remove another field so I can hear it without a tone in there?

I do not fully understand this whole concept, please correct anything I may have said wrong.

Thanks!

 

[JoeyC]

You do not need to have a CTCSS tone entered to hear anything. Doing so, acts as a filter. With a CTCSS tone you will only hear the radios that are transmitting that subaudible tone on the frequency. With no CTCSS tone programmed, you will hear everything on the freq within range. If you are not hearing anything on those freqs set to CTCSS search then there is nothing being transmitted.

 

[Fsher21]

Thanks for the help! Now to find an antenna.

 

[Ed_Seedhouse]

You do not need to have a CTCSS tone entered to hear anything. Doing so, acts as a filter. With a CTCSS tone you will only hear the radios that are transmitting that subaudible tone on the frequency. With no CTCSS tone programmed, you will hear everything on the freq within range. If you are not hearing anything on those freqs set to CTCSS search then there is nothing being transmitted.

This is useful for transmitters that suffer from intermod from other nearby transmitters.

Here in Victoria B.C. the main Ham transmitters sit on a mountain with dozens of other commercial antennas some of which put out quite a hunk of power. One of them has a CTCSS tone and when I programmed that into my scanner it always comes through cleanly. Another does not, and I gets hits several times a day which trip my squelch and make a loud annoying noise.

Also there are two repeaters nearby that are on the same frequency but have different CTCSS tones. One is in town and the other is across the pond in Port Angeles, which might as well be local in my location even though they are in different countries. With my base antenna, both come in at a full five bars.

Adding the CTSSS tones in allows my scanner to differentiate. Of course when they are both going at the same time there will be a problem despite the CTCSS, but fortunately that doesn't happen all that often. I also generally scan for "family band" transmissions (which the road sign crews use when the road is being paved or repaired) and I leave the CTCSS off because I want to hear everyone on all channels that may be broadcasting.