One more note about feeding the Cobra as a T on 160. To do this you will probably need two sets of feedlines, and a switch box out by the radial system. You could use open wire to feed the Cobra, and
The problem with end feeding a half wave wire on 160 (in this case configured as an L) is that most people who operate 160 soon discover that you need an amplifier. That translates into big voltages
..."I'm not buying that! Current flow depends on impedance, R+jX, not radiation resistance."..... Ah, but it's confusing. For a short vertical that is not tuned to resonance, if the source is a volta
Martin wrote: ..."When I said a short vertical, I meant electrically short, i.e. << one wavelength (and also << 1/4 wavelength). Such a monopole above a ground plane always presents a high impedance,
G3TXQ wrote: I don't know of any programme that will calculate the voltages and currents - I just did it the "hard way" with Smith Chart and a pocket calculator EZNEC will give it to you. To get the
Lee Here are a few items to consider about your planned 160 antenna. Warning: This post is long and has a lot of detail which may bore some of the readers, but I'm sure Lee will be interested. Lee sa
Wrong question. There is no best antenna for 160. I can give you a link to a construction project for a three element 160 meter Yagi if that would interest you. You would then need a four element Yag
Across relay coils I recommend using a zener rated at at least 3 watts and preferable at more than that. Look for one with a high current surge rating. The reason being that lightning can sometimes i
WR8K wrote: Are diodes across the relay coils necessary? And if so, how can I detect a failed diode (a short, correct?) before turning on the power? I answered the first part of that with my first po
Here is an article that should answer your question: http://www.vk1od.net/multibandunloadedvertical/index.htm Also notice the paragraphs about the balun used in some of these antennas. Here is a link
Here is some data from one supplier. This might be good if you know exactly what type of pipe you are buying. http://www.hollaender.com/files/1/Tech_Data/handraildesign.pdf Jerry, K4SAV _____________
Feedline radiation is the same way that the TAC antenna gets an SWR of 1.0 on 40 meters from an antenna that has a feedpoint impedance close to 5 ohms. It appears your Zero Five conclusions are corre
K8RYU wrote: "A couple comments. First off, the thing can be tuned from the shack with an "unbalanced openwire" feed, simply a wire carefully insulated from earth with, ideally, a number of parallel
Here is your answer: http://www.vk1od.net/antenna/multibandunloadedvertical/index.htm Jerry, K4SAV _______________________________________________ _______________________________________________ Towe
The characteristics of the cap you need to tune an inverted L to resonance on 160 has a lot to do with the shape of the antenna. In some cases the cap may be very large value, have a fairly low volta
I would expect that 120 of Rohn 45 with a three element 40 meter Yagi on top to be resonant somewhere around 1.6 MHz. Since it is so tall, if you match it with a series cap, the feedpoint impedance w
I just threw together a quick model, and it looks like my estimate was too high on the feedpoint impedance. It should be close enough to 50 ohms that a single cap should do it. Resonant frequency was
You can whip one up very quickly with Elsie. It's a free program and very simple to use. Get it here along with some other good stuff on this page: http://www.tonnesoftware.com/index.html The freebie
There are several ways to make a dipole cover all of 75/80 meters, and also many ways that don't work. A double Bazooka doesn't cut it. It only provides about 14% increase in bandwidth at the expense
N3OX wrote: An important thing for the original poster: the lake has to be very large for this to work,............... Also it has to be very deep. Those gain numbers you got from EZNEC assume an inf