Its pretty simple to do in EZNEC, Bill. All you need to do is to model two yagis at the appropriate heights above ground, and then drive each one with a 1 amp current source. EZNEC lets you specify t
Rohn specifies fine threads on their tower bolts (at least for Rohn 25), but no lockwashers. Presumeably this is because the nut on a fine thread bolt has to turn farther to lose its preload and come
loose It's helpful to visualize the physics if you unwind the screw threads into an inclined plane. The fine thread looks like a long gradual inclined plane, whereas the coarse thread looks like a st
Does anyone know where I could find a center conductor splice for some RFS/Cablewave Systems 7/8" Spir-O-Line hardline? The center conductor splice is a 0.33" diameter x 2" cylinderical sleeve made o
What alloy are you using, Tom. Most of the stuff you can buy at home box stores is for plumbing applications (96%Tin, 4% Silver). This stuff has a low melting point and the resistance is fairly high
I don't think what you are saying is correct, Jim. If the noise is uniformly distributed, increasing antenna directivity will not change the total noise power received. The higher directivity antenna
Offhand I don't know the value of the modulus for a typical EHS guy wire, but just imagine for a minute how hard you would have to pull on a guy wire that is already tensioned to 600 lbs in order to
Seems about right to me. I paid about $1/pound for a couple big sheets of scrap that I got from the local metal dealer. I think the world price for copper hovers right around this figure. Mike, W4EF.
I tend to agree with Bill, Jim. You might want to include a bracketed Rohn 25 tower as a "low cost" or "entry level" option. I had a very similar installation to Bill's when I lived in Florida (35' o
Hey, there is one guy on the Ten-Tec reflector whose callsign "N4LID" appears in his email address alias. Now that is a guy with no insecurities :) 73 de Mike....uhhh.......W4EF................. 2X1
Actually the guys who appear not to be signing any callsign at all are really just signing with their 0x0 calls, Jerry. Their 0 x 0 callsign indicates that they have reached the pinnacle in the amate
This reminds of something that I observed about 18 years ago when I was going to school at Ohio State in Columbus. Steve, N8SM (now sk) and I were at the radio club on a cold windy winter afternoon.
One big advantage of the quad that is often neglected is turning radius. Quads are great if you are in a tightly confined where you can't afford to have long yagi elements hanging over property lines
I just finished building and installing an 80/75 meter "fan" dipole for the local club stations which uses pieces of black Delrin for the center and end insulators. I had the black Delrin laying arou
Probably the easiest thing to do would be to use two ring rotator control boxes with a common set of external double pole CW/CCW switches wired in parallel with the individual CW/CCW switches in each
Nope, nothing special, Derek. You could even use wire nuts, and the resulting impedance bump at HF frequencies would still be inconsequential. 73 de Mike, W4EF................................. anothe
Noel, I respectfully disagree. If someone asks about how to rotate a particular antenna, don't you think it would be appropriate, and, in fact, expected that people might share their experience with
It might be interesting to take a freshly cut try stump (so 8 to 10 feet), wrap it with copper sheet, bore the center out for a copper pipe, and the do some impedance measurements of the resulting co
It is very relevant. In fact it is relevant in the same way that the wire diameter in a two-wire parallel transmission line is relevant to the impedance of the line (the mathematical expressions are
If you have a NEC program like EZNEC, Joe, you can actually model a detuning shunt arm and then look at the current in the tower and in the shunt arm. When the properly adjusted the current inside th