What you should be aiming for:
For communication purposes, your transmitted audio should be easy to understand. Especially in today’s noisy environment or during a pile up. I’ve been using my Clansman RT-320 on 40 metres and, with only 30 Watts and an end-fed antenna, I’ve been hammering my way through pile-ups as if I’m running massive power. It’s the audio that does it. The Clansman is a military radio and the military need good, clear and understandable communications, often under adverse conditions.
| A good SSB signal should sound: | It should not sound: |
| Clear Punchy Narrow |
Bass-heavy Boomy Hi-fi |
IC-7300 SSB Audio Settings for optimised communications:
I’m using an Icom IC-7300 which is an excellent rig for SSB. It’s flexible but, easy to over-process if you’re not careful. Here’s a clean, communications-focused setup that is ideal for reliable readability rather than what may be described as hi-fi audio.
Microphone Gain:
Start around: 35–45%. Adjust while speaking normally.
ALC:
The meter should just move on peaks. If ALC is constantly high, reduce the microphone gain.
Compression:
Set this to 3–5. Low to medium. On the meter, compression scale, aim for 5–10 dB peaks.
The more compression, the louder average signal but, if it’s too high, your audio will sound harsh and distorted.
Adding Equalisation:
Many times, I’ve heard stations using SSB with far too much bass. Presumably, they’re trying to achieve hi-fi quality audio? Personally, I think it sounds terrible. But, apart from sounding terrible, it doesn’t do them any favours. I heard a chap the other day running something like 600 Watts. Massive signal! But, he had so much bass that it wasn’t easy to hear what he was saying. Obviously, ear-piercing earache audio like the old carbon microphone telephones isn’t pleasant to listen to. But neither is heavy bass.
Whatever radio you have, do try to set it up properly. Especially if you want to work DX and get through pile ups. Read the manual and ask someone local to listen to your transmission. There’s another aspect to having incorrect settings such as increasing bass response. It’s a waste of power. Also, enhancing bass response increases the bandwidth of your transmission. If it’s hi-fi quality you’re after, use amplitude modulation.
More coming soon…