Handbook, chapter 11. The transceiver: what all those knobs do
Twenty knobs and thirty buttons. The manual describes each one separately and does not say the main thing: which are used daily, which are switched on once a month, and which one you need only get wrong once to hear about it on the air afterwards.
That is what this chapter is about.
Press any of them
RF gain — turn freely. Takes sensitivity away from the receiver. It sounds harmful, but it is in fact the main knob on the low bands at night: turn it down and you remove the noise and start hearing a weak station better than at full sensitivity.
The panel is generic: on your set the controls sit differently and may have names of their own. The functions are the same, and it is the functions that matter.
Three controls that work every day
Volume. Set so that the band noise is barely audible, not so that things are «nice and loud». Loud noise tires you out within an hour to the point where you simply miss a weak station.
Filter width. The most underrated control on the set. Voice needs about 2.4 kHz, CW 500 Hz, and in a crowd 250. Narrowing the filter by a factor of four removes three quarters of the noise, and those are clean decibels that cost nothing — unlike an amplifier.
RF gain. The knob beginners are afraid of, because «why would I reduce the sensitivity». The point is that at night on the low bands the receiver hears not the signal but atmospheric noise, and the set's own sensitivity is more than enough there. Turn the RF gain down: the noise falls, the signal stays, and a weak station becomes easier to hear than at full sensitivity.
What to switch on when needed
NB, the noise blanker. Against short sharp crackles: car ignition, switching, electric transport. Useless against steady noise, and it distorts loud signals. Not worth leaving on all the time.
NR, digital noise reduction. Makes the sound pleasanter and almost never more intelligible. At the threshold it easily eats the weak signal along with the noise. A useful thing that is easy to harm yourself with.
RIT, receiver incremental tuning. Shifts the receiver without moving the transmitter. Needed when the other station is slightly off your frequency and you cannot move your own. And here is the classic first-year mistake: forgetting to switch it off. Afterwards it seems the set has gone deaf.
AGC. Levels the volume between a loud station and a quiet one, and without it listening is impossible. There are usually two settings: slow for voice, fast for CW and for signals with fading.
The one control nobody touches
Microphone gain. It is set once — by the ALC meter, following the set's manual — and never moved again.
The reason is that beyond a certain point it does not add volume. It adds distortion: the signal spreads into neighbouring frequencies, and what sounds «louder» to you sounds to the station next door like a rasp on top of their contact. It is the commonest complaint on the air, and almost always this knob is the cause.
ALC is not a loudness indicator to be «pushed into the green». It indicates that the transmitter has already started limiting itself. The right setting of the microphone gain is the one where the ALC needle barely moves on voice peaks, not the one where it sits at maximum.
Not on the panel, yet used all the time
The attenuator. A 10–20 dB button. Needed by day on the high bands, when a powerful station is working nearby and the receiver begins to choke. The sign is that the noise rises as the neighbour appears.
The preamp. The reverse: it adds sensitivity on 10 and 6 metres, where the band's own noise is low. On 80 and 40 metres it gives nothing but extra noise.
The rule is simple: preamp on the high bands, attenuator on the low bands and by day.
Where a beginner should start
For the first week three settings are enough:
- Volume — at the point where the noise is barely audible.
- Filter — to suit the mode: wide for voice, narrow for CW.
- AGC — slow.
Switch everything else off and leave it alone until a particular problem appears that a particular control solves. A set configured «just in case» hears worse than one with nothing switched on.
Next — chapter 12, safety: the one chapter after which nothing happens.