Getting the best from your radio often requires you to read the jolly old manual (RTFM), or just twiddling the various knobs until the right thing happens. One of the under-used functions is the RF Gain control. But why should you want to reduce the sensitivity of your receiver?
An effective way of making CW easier to copy is to drop the RF Gain a little and (if you have IF-based DSP) to reduce your filter bandwidth to 500Hz or less. If you’ve found a strong (say, S7 or better) signal on 20m and you’ve got an S2 noise-floor, then you can back-off the receiver a little to offer a better signal-to-noise ratio.
By following this practice, the reduction of the RF Gain acts as a rudimentary Squelch function and providing the strength of the CW signal reaches the RF Gain threshold – will make it all the more easier to copy. If your radio doesn’t have a dedicated RF Gain control – it may be that the Squelch knob can be set to do this via a menu option.
In the following example, you can hear how a filtered signal compares to an unfiltered one:
CW Example – Narrow Filter (100Hz) with RF Gain reduced vs “SSB” width
Another good reason for narrowing the filter is to attenuate (or completely remove) the presence of adjacent signals. The sound of other (and stronger) CW signals elsewhere within the pass-band can make it difficult to hear the one you’re trying to concentrate on. This also works with other narrow-band modes, such as PSK and RTTY – get rid of the strong neighbours and concentrate on that weaker (and more interesting) signal.
The same approach works for SSB – If signals are strong, you can wind the RF Gain down a bit and enjoy a clearer sound – as this example shows:
SSB Example – 2400Hz with RF Gain reduced vs standard RX setting
Of course, the bands often have a habit of getting the better of us: Rapid QSB and adjacent signals popping-up can clobber your finely tweaked settings at the worst possible moment – but that’s half the fun. Modern radios also offer a number of AF (audio) receive features such as APF (audio peaking filter) as well as EQ settings to tailor the sound of your radio to your ears, the radio’s surroundings and whatever speaker you’re using.
Knowing how to use the various receiver functions to your advantage makes for a more enjoyable experience!