Saturday, June 1, 2013

RF in the Shack

After finally getting my RF rig set up an tested, I've had a few unusual problems which have convinced me that I need to re-think how I am doing things. In this post, I will talk about the common problems that I am having testing out my new radio, and what I have done to mitigate the problems.

RF in the mike is a pretty common problem, that usually has one of two main causes. It will lead to some serious issues, namely having very distorted audio. This can be caused by:

1. A poor SWR will result in lots of RF energy reaching your transceiver, often transmitted over the insulator. This in turn can reach your microphone, causing issues.
2. If your antenna is too close, or you otherwise are broadcasting power close to your transceiver, it can get in to the mike as well.

Some symptoms you might notice are:

1. Your SWR meter pegs at the highest power when transmitting SSB.
2. Frequent complaints of poor audio, despite a strong signal.

What can you do to fix it?

Well, the first thing is to track down the source. In my case, I was using a ladder line antenna too close to a metal surface. This caused all sorts of interference problems, despite my antenna being 30 feet away from my transceiver. The solution was to run a coax cable in the area near my metal area. It worked fine for a while, because the ladder line ran initially far away from the metal, but with time, it came closer and closer to the metal, eventually causing significant issues. I noticed it particularly on higher frequencies (10m), but it worked it way down to 40m.

If you aren't running ladder line, and are confident that you don't have strong RF signals near by, then you might invest in some ferrite clips, specifically to clip to your wire line, and possible other items which are receiving interference. I've been using them, to much success. I bought some on Amazon, which seems to be the best place to get them, I've provided a few links to the types I selected. Try to buy the right size. The right size should fit snugly on the wire, without any spare room if possible.

Bottom line is, RF in the shack is a solvable issue, and communication is much better after you've solved it. Good luck!

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