Why do some of our repeaters have “Split-Tones”?
Simple. We operate our repeaters at maximum performance. This means both higher levels (watts) of transmit power and at the same time, high sensitivity receivers using preamps. Most operators might not know what this means, that’s OK. High output power (when allowed) and sensitive receivers means that isolation between the repeaters receiver and transmitter are critical. Otherwise known as duplexing. On 2 meters we are forced to 600Khz offsets, this is a tight window. Filtering, cable, antennas, site noise and more all play into this delicate dance at commercial tower sites.
If your repeater sends and receives the same tone, you must guaranty that there is enough isolation. In the winter, at extreme locations, snow and ice will greatly effect your system. Noise changes, reflected power changes and most importantly, broadcast noise changes. Add a FM or TV broadcaster to that and you have a mess. This is why we will split tone. We want to offer a way to quiet or lock our mobile/portable/base receivers. Doing this will keep your speaker very quiet and no squelch burst will be herd each time the repeater transmitter drops.
Very few ham radios support this. Kenwood 710GA supports split tone along with the Yaesu FT-2980…… All commercial radios support this as its been done for 30+ years this way.
You don’t have to use receiver decode, its an option for you as the operator locally.
All our repeaters encode (send) a lower tone and decode (listen) for a higher tone……
a repeater encodes 91.5 and decodes 136.5
this means YOU, the operator will:
Encode 136.5 (send to repeater)
Decode 91.5 (listen from repeater)
If your radio does not support Split-Tone, then just encode 136.5 and that’s it.