Set RF Gain in AM, FM, or SSB modes

Setting RF gain and squelch properly are vital to maximize receiver range (how far you can hear) while minimizing listening annoyance (background noise). It’s important to have a radio with NRC digital noise reduction, which can help reduce background noise and make listening more pleasant, especially in AM and SSB modes. CB radios with NRC are the same price or cheaper than 1990’s style CB radio without NRC, despite NRC being such a significant improvement to the listening experience. The technique to optimally adjust RF gain and squelch is distinct for each of the three main modes: AM, FM, and SSB (LSB/USB).

Separate and independent of RF Gain, Squelch, and NRC are the ANL (Automatic Noise Limiter) and NB (Noise Blanker) features. ANL and NB can often be “off” in base station or vehicle engine not running scenarios, which can reduce distortion of received signals, but with the penalty of more background noise. In scenarios with significant engine noise, ANL and NB can be turned on to reduce engine noise, but with the penalty of some possible distortion of received signals - often the benefit of ANL and/or NB outweighs the distortion penalty in noisy environments.

AM setting of RF gain and squelch

For AM, set the squelch to manual and open (you hear noise), then set the RF gain like:

  • knob: starting from fully clockwise RF Gain, turn counterclockwise just until the background noise noticeably drops.
  • menu: starting from “off” RF Gain, increase the number until the background noise noticeably drops.

This is the point where the RF gain is just enough to amplify the desired signal, but not so much that it amplifies the background noise and makes listening annoying. Now, turn up the squelch just till the noise stops - or turn on auto-squelch. This will maximize range on AM while helping reduce background noise. If there are DX signals via skip or a noisy area, adjust the RF gain and squelch accordingly to find the best balance between receiver range and noise reduction.

SSB setting of RF gain and squelch

On SSB modes (LSB / USB), across radio models from inexpensive to top-end, the squelch generally is too aggressive and will reduce receiver range if set to block all noise. It can be a better practice on SSB to not use the squelch if maximum range is desired, using only the RF gain to set noise to a low level. Experiment to find if squelch is useful for your scenario - perhaps if no conversation is happening, just close the squelch, and when a conversation starts, open the squelch to hear at better sensitivity.

FM setting of RF gain and squelch

On FM, the squelch is generally more effective at blocking noise than in AM or SSB modes. You can leave the RF gain as set in AM or SSB modes, or to maximize range, turn up the RF gain until the S-meter begins to indicate a signal, then adjust the squelch to just block the noise - or turn on auto-squelch. For DX communications, opening the squelch on FM will help just like on any FM radio - but of course this will let in noise between voice transmissions. Radios with NRC digital noise reduction will help reduce the noise of open squelch somewhat.