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Radio Basics

Additional controls

One only needs to see an advertisement photo to know there are many more controls on a modern day, high end transceiver than the four I mentioned in section one. Just as technology has hidden many of the controls for some users, it has added many, many more controls for those who want them(and are willing to pay for them!).

I won't make any attempt to cover any significant portion of them here; I'd be hard pressed to get them all in a single book anyway. Many such controls are much better learned and appreciated when the need for them arises ... and they don't always make a lot of sense until you see the need first.

I will, however, touch on a few to get you started. These are easily understood, and commonly used controls that are only a bit above the primary controls in section 1. You'll likely start working with them shortly.

RF Gain

The name may start to sound a little cryptic, and first impression might be that this is just another volume control. Of course thats not the case, and knowing the difference is what makes this control very useful.

The difference in this control is the point at which it adjusts the volume. The conventional volume control adjusts the loudness after the radio is all done with its magic tuning/demodulating/filtering/etc. The benefit of the RF gain control is that it controls the 'volume' our radio itself hears. This is useful because we can turn down signals that are overwhelming the radio's "ears", thus getting them back to a level where the radio can 'fix' them for us.

Mic Gain

This can be quite simply thought of as controlling the volume level that we are transmitting; and many non-informed radio users will think the only logical setting is wide open so they 'come-in' louder than any other station.

That's of course not at all true.

The purpose of this control is to adjust our microphone's ability to pick up our voice. Some mics are more sensitive than others, some people talk louder than others, and some people hold a mic closer than others. All these factors need to come together and arrive at the correct volume our radio needs to fully 'modulate' the outgoing signal without over doing it. Too little, and your voice will be very soft on the other end. The receiving operator can turn his/her volume up to compensate, but that also turns up any static as well. On the other hand, and this is the part many operators don't realize, if we have it too high our voice will be distorted and difficult to listen too. Causing interference to nearby channels is also very possible. As you can see, it is quite important to get this control set correctly!

Clarifier

Now this one really sounds like something we would want to turn wide open all the time. We want it as clear as we can get it!

Ahh, nice thoughts! Too good to be true of course. This control actually helps us only when using SSB modulation; and provides us with a way to receive on a slightly different frequency than we are transmitting on. Not at all what the name might imply initially! For various reasons, there can be a slight frequency shift between the transmitting station and the receiving station. When using SSB modulation, this frequency shift causes a 'Donald Duck' effect on received voice; and the clarifier allows us to adjust that out. Sorry, no magic wands here!

RF Power

This own controls how much power we are sending to our antenna; and once again more is certainly not always better. First of all, for ham radio operators, the FCC requires us to use the minimum power necessary to acheive the desired communication.

Obviously, if we don't use enough the other station isn't going to hear us clearly, if at all. Thats pretty obvious, so I'll discuss a couple of reasons why we don't want to use too much.

Whatever frequency we choose to use, there will always be someone else using it as well. Think of it as a large group of people in a room together. If we start talking to the person next to us very loudly, it makes it difficult for the people at the next table to hear each other. Radio works very much the same way. If the station we want to talk to is on the next block, using a 1000 watts of power will drowned out the guys in the next town that are trying to talk to each other. There is no reason to do this; we can turn the power down to a point where our next door neighbor can hear us perfectly well - yet not even be noticed 10 miles away. Thus, both parties can communicate at the same time using the same frequency without bothering each other; simply by turning the power down.

Another problem that often arrises is reflected signals. This is common in city environments, where there are many large buildings, etc. It can also occur with terrain features, but thats less common. What happens is that the signal goes to the receiver by conventional line of site as we'd expect; but also travels some other direction, and then gets 'bounced' back to the receiver. Of course, this second signal has further to travel so it doesn't arrive at the same time. The result depends on the exact timing; but is typically an echo effect - which can make it difficult or impossible for the receiving party to understand us.

High power settings, necessary or not, also increases the chances that we will cause local interference on very different radio systems. We only need to get our signal into our neighbors TV with enough power to overwhelm their TVs filter network to cause interference. Of course, we want to avoid that can of worms!