Contents
How do I know if I have RF in my shack?
Use a balanced antenna with good coax. You don’t need a probe. Just waving a flourescent tube along the outside of your co-ax when keying up will tell you if there is any.
How do you keep RF out of the shack?
One easy way is to roll up 10 to 20 feet of coax and tape it with electrical tape, which creates a form of a choke balun and helps keep the RF off the outside of the cable. You can also use ferrite cores—it usually takes quite a number of them.
What is RF grounding?
In my opinion, an RF ground is something that presents a low impedance at all frequencies of interest on the desired ground surface. All frequencies of interest usually means just the transmission frequency and all spurii. Spurii usually include harmonics, but may include mixing products.
What are the effects of common mode currents?
Likewise if RF couples in, it also couples out to the antenna. This can increase noise and interference to desired signals when receiving. Inside the Ham shack or along the antenna feed line, common mode currents are responsible for unwanted noise ingress, RFI, RF burns, and a host of other maladies.
What causes RF in the shack and computer crashes?
Our first common assumption is that RF “in the shack” that distorts our audio, causes computer crashes, or (worse yet) causes RF burns is caused by inadequate station grounding. RF “in the shack” often occurs when we use makeshift antennas, such as a longwire or some other single-wire feed system.
How does common mode work on an antenna?
Common mode currents effectively bring the radiating part of the antenna system down along the feed line or the antenna’s metallic supporting structure. Common mode currents can extend all the way to the desk and station equipment, and even out through power line connections.
What causes high RF levels in a ham shack?
RF “in the shack” often occurs when we use makeshift antennas, such as a longwire or some other single-wire feed system. Obviously, bringing a longwire or some other antenna directly into the ham shack or placing an antenna near the operating position will cause high RF levels and associated problems.