Think AM Broadcast -- according to IEEE data, on average, the energy in lightning has a VERY broad peak around 1 MHz (so broad that there's lots at 2-4x that frequency and 0.2X that frequency). It is
Not ideal. The BEST, by far, is for all cables -- power, antennas, CATV, telco to enter at the same point so that the ground connections between them can be as short as possible. Remember that the MO
VERY good advice. As it turns out, I'm about 90% done with a tutorial on RFI and ferrites that includes a discussion of baluns, a lot of measured data, and specific advice on troubleshooting RFI and
http://audiosystemsgroup.com/RFI-Ham.pdf is a tutorial that, among other things, attempts to answer most of your questions and many you probably never thought to ask. It's a work in progress, posted
Robert, Consider a half wave dipole sloping off the tower in the desired direction(s). I've done that at an old microwave site that has a massive 140 ft tower (roughly 10m square at the base, 8m squa
You didn't say how much power you wanted to run through it. My tutorial on RFI includes an extended discussion of choke baluns. I suggest you study it before proceeding. It will also point you to som
There are some serious misconceptions here. Transformer baluns and choke baluns are fundamentally different. A transformer balun MUST have low loss (all the transmitter power goes through the core, s
Until I moved to California this spring, I never had a decent antenna, let alone two decent antennas. Now that I have some good high dipoles and a pretty good vertical, I've learned firsthand that ve
An important quibble about the word "polarity" -- the correct meaning is describing the voltage reference for the signal in an electrical circuit -- what in the old days, before we knew better, we c
Ferrite chokes are essentially very low Q parallel resonant circuits. Antenna analyzers are not very useful for measuring ferrite chokes, for at least two reasons. First, they have a fairly low input
I agree (although it has to guess at the sign of the impedance). The most important thing is that we understand the limitations of our test equipment, which you clearly do. 73, Jim __________________
Good question. See below. Yes. If you're buying surplus clamp-ons and cylinders used for RFI suppression, it's most likely that they're #43, and a single turn (that is, the wire going through the cor
That's pretty vague. What sort of trouble? What sort of system? What is the ethernet doing? Ferrite chokes can effectively kill common-mode antenna behavior of ethernet lines at HF if you use the rig
I would start by listening for Ethernet birdies on the frequencies listed in my tutorial that are on the ham bands that bother the ethernet system, and adding ferrite chokes as described in the tutor
Study the tutorial. It's written for guys with your background. Jim K9YC _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTa
The mismatch between 75 ohm cable and a 50 ohm load is no big deal, except to the extent that the somewhat higher SWR might cause your transmitter to be a bit unhappy and pull back the power. This is
Yes. I have been quite pleased with Hamsticks. Not as convenient as a screwdriver, but they work fine if you install them well, especially on the higher bands. The key to a good mobile antenna is a g
I've always been primarily a CW op, even in the car, although I will work SSB on long trips. My first HF mobile rig (back in the early 80's) was my only HF radio, a TenTec Omni A (bought new, when it
You can increase the power handling and performance of any choke balun by adding a second choke balun in series with it (that is, between the first balun and the transmitter). See the tutorial below
Hi Dennis, I have five of the big clamshells on the positive lead right at the battery, and several turns around the toroid where it runs as a pair. I haven't had time (or the motivation of a long ro