CB radio delta tune knob

June 27, 2022

For those using a legacy CB radio like a Cobra 25, 29 or Uniden PC 78 or similar, one may notice a “Delta Tune” knob. This knob is normally set to the center position. In case of strong adjacent channel signals, the Delta Tune can be adjusted to shift the receiver tuning down in frequency (counter clockwise) or up in frequency (clockwise) to improve reception of weak signals on the desired channel. The amount of shift is radio dependent, perhaps 1 to 2 kHz, and is not a precise adjustment. The Delta Tune doesn’t help splatter from overmodulated signals, but it can help with strong adjacent channel signals that are close in frequency to the desired signal. For example, if one desires to talk on channel 10, but there is a strong signal on channel 11, turn the Delta Tune knob counter clockwise to shift the receiver tuning down in frequency to improve reception of weak signals on channel 10. Tuning too far may cause the desired signal to be shifted out of the passband, so adjust the Delta Tune knob while listening to the desired signal. Delta Tune affects only the receiver tuning, not the transmitter frequency.