It seems like you would want to use hardened steel instead of aluminum for the knife. How does it hold up? Are you saying you only cut a 1/8" wide slit? That seems too narrow. Rick N6RK _____________
I am trying to do a simple wind pressure calculation on an antenna, but I am confused about how to do it. I see conflicting information on towertalk archives and various ham vendor sites. Let me see
Here is a quote from the YS manual: Somewhere on the YS web site, there is a justification, such as it is, for using this obsolete formula. Applying it to the example I gave would give an effective a
Here's my take on it: Economic tradeoffs: Considering that 14THHN is about 2 cents a foot at Home Depot, etc., how much are you earning per hour to make all those solder connections to save $50 or $1
That's interesting about what Tom told you. I remember him giving a talk at Pacificon a few years ago where he said 2 dB makes a huge difference in a contest. The other thing to consider is that if y
I have an array like this, except it has 7 elements. One in the center and 6 in a circle of 3/4 wl diameter. However, it is an all driven array, not parasitic. There are 3 phasing networks. One fires
White out pens are also excellent for marking ferrite cores. For big cores, you can write with the white out pen directly. For small ones, made a while rectangle, let it dry, and then use a regular p
The following lumped element circuit is equivalent to a quarter wave of 75 ohm line: --CAPACITOR--CAPACITOR-- INPUT INDUCTOR OUTPUT --CAPACITOR--CAPACITOR-- (Set your font to Courier for this ASCII a
I characterized a bunch of speaker cable. It seems to run between 100 and 200 ohms. Never seems to get down to 75 ohms. I am using some 150 ohm speaker cable in my 50 ohm to 450 ohm balanced to balan
I have been studying the wire market for several years. (I know, I need to get a life :-) Anyway, I have noticed that, for some unknown reason, 14 THHN is considerably cheaper than bare 14 gauge wire
What I did on my 20 acres was to use two 300 foot tape measures to form triangles. I started with a base line down the center of the road (which runs within a degree of N-S) and then triangulated to
Some people have asked about my two tape measure technique for laying out antennas. Perhaps it would be useful if I posted a tutorial to the reflector with the details. Measure out 200 feet along the
I believe the quadrature phasing is referred to as cophasal in antenna textbooks, and the more aggressive phasing is referred to as Hansen-Woodyard phasing. Basically, just model the array on EZNEC
The "official" outer diameter of anything that is 1 1/2 inch iron pipe size is 1.900 inches. 2 1/8 tubing with .058 wall fits over this with a .0545 inch gap (at least theoretically). What I do is us
due a I modeled a 4 square of 1/2 wave verticals on EZNEC and it worked fine with one caviat: if you want to feed the verticals at the bottom, you must use voltage sources. Having said that, I suspe
Rather than the cumbersome test you suggested, simply measure the Q of the trap with a Q-meter or other impedance measuring equipment at low excitation levels. Then you can calculate the loss for a g
I've done a lot of measurments of verticals, and I wanted to get the best possible answer for resonant frequency and feed resistance. My 259-B just wasn't accurate enough for this task, (nor does MFJ
Maximum bending moment is proportional to the difference between the cubes of the O.D. and I.D. An approximation to this is that for constant wall thickness, max moment scales as the square of the di
The secret to using 4 inch irrigation tubing is to never drill holes in it. Only clamp it using 4 inch Sch. 40 PVC pipe as a collar. The nominal I.D. of that pipe is 3.999 inches so it is a perfect f
It is no problem to walk up 60 feet of 4 inch irrigation tubing if you have a helper pulling on a rope to assist. Using the falling derrick method, one person can do it. See: http://www.karlquist.co