NEC modeling of closely spaced wires can be accurate. I have done extensive modeling of closely-spaced wires at less than 2 inches at HF, including multiband feeds similar Force 12's. When doing thi
W8JI: Tom is right about combining antennas or radios at RF and audio. Phase and amplitude effects will cause cancellations that negate the benefit much of the time. But my experience is different th
from VK6VZ: Steve and all, At W4WA in the CQ160 CW, when running, I often listened on two receivers, one in each ear. Depending on the propagation and activity, the following combinations were tried:
Chuck and all, Very short "Beverages" can work quite well down to 250 or 300 feet, but they almost always require a low termination resistance. A reactive (inductive) termination can improve the f/b
Ford Comments inserted below...73, Gary, K9AY As I understand from Andy Ikin, Wellbrooke is making the antenna pretty much identical to my QST article (Sep '97). Their distance limitation might be fo
Geo, 43 material is commonly used in EMI filtering applications where looser manufacturing tolerances may be acceptable. It could be the cores you have were made to meet a spec of "guaranteed minimu
Bill 1. Antennas are "reciprocal," meaning transmit and receive characteristics are identical. Reciprocity is a fundamental antenna principal. 2. Radiation from a balanced feedline (or from coax in
Topbanders: After reading W7IUV's comments and other recent posts on various members of the "loop-like" RX antenna family, some of my accumulated notes may be useful. First, remember that the EWE, K9
W4EF: Mike & topbanders When I lived in the suburbs of Denver a few years ago, I could NOT get any help in S/N using shielded loops or EWEs. I even decided to search the neighborhood for noise source
Bruce The scheme you propose may prove unsatisfactory. The Pennant and Flag antennas are independent of ground and must be isolated from the feedline. A preamplifier will almost certainly have a comm
FWIW, I noticed an interesting phenomenon in the 160 contest. Both VK6HD and VK6VZ were very loud (make that "HUGE") for quite a while Saturday morning, yet they were coming in on quite different pat
Ken and all, Think about this setup for a moment -- you would create a transmission line that was shorted at the top, with the shield grounded at the bottom. The net result is that all you have is a
Jeff If the station on 610 is local, do a little "sniffing" nearby to your station to be sure that rectification is not the cause of the harmonic. For several years, I lived 1-1/2 miles from a 5kW st
Tom has given us some excellent suggestions. Let me also suggest using a SPECTRUM ANALYZER to identify suspicious signals. There are industrial sources of tens of kW at 6.78, 13.56 and 27.12 MHz that