Monday, February 16, 2009

The RF Gain Control - Unsung Hero of Your HF Rig

A lot of times when I talk to Hams that are new to HF operation they mention how bad noise (QRN) and interference (QRM) can be. They often wonder whether adding an external DSP or internal crystal filters will eliminate the problem. Well, these accessories can help but new operators, and perhaps you as well, may already have one of the most effective tools in combating interference and noise.

The RF Gain control on your transceiver is the unsung hero of HF operation. It provides a variable means to reduce the strength of all of the signals coming in to your receiver. Used properly it can very useful in picking out just the signal you want. Here are the basics...

First off, if the band is just generally noisy like 40 and 80 meters so often can be, use the RF Gain control to reduce the static and noise levels you hear when you are not tuned to a signal until the noise is just barely audible. Then starting scanning for stations to work. If you're not trying to snag some rare DX station or pass an emergency message then there's no reason to make your rag chew tedious by hearing all that noise. As long as you can hear the other station does it really matter if the meter indicates S9 or S2?

Next, lets say you find a station to work but there is some QRM or QRN making it tough to hear them in spite of the adjustment you made earlier. Try this: Turn the RF gain control to minimum. You may hear nothing at this point. Then, turn the volume control up very high. You still may not hear anything. Now, use the RF Gain control (not the volume control) to control the volume of the station you want to hear. A lot of times this will make the easy to copy while drastically reducing the junk you don't want to hear.

Remember to turn down the volume control before you increase the RF Gain when you move on to the next QSO or things will get VERY loud! Once you practice this a little and get used to it you'll wonder how you ever got along before.

1 comment:

Anonymous said...

This is an important point. The RF Gain control is the singularly most underutilized tool in the ham tool box. It is all about signal-to-noise and the RF-Gain control is the best tool for minimizing noise while maximizing signal.

// K8JHR //