So how much delay is tolerable? It takes me 20-45 minutes to drive back to the ready mix place 1 1/2 miles away, get reloaded, and drive back. After 45 minutes, I can at least poke a hole in the pre
Yes, but the tensile strength of concrete is very low < 1000 PSI. The rebar provides most of the strength anyway even in a monolithic pour. Rick Karlquist N6RK richard@karlquist.com www.n6rk.com www
I thought of that a long time ago, but I've never modeled it. However, your premise that "it works with coax" is somewhat questionable. It doesn't work all that well with coax and you need a boatloa
And where do I buy them to get them for "little cost"? I need to get some ASAP. Rick Karlquist N6RK richard@karlquist.com www.n6rk.com www.karlquist.com
Everytime this subject comes up, someone mentions the water pipe method. Around here, that works wonderfully for a few feet until you hit the "cemented hard pan". Which is waterproof. Then you get ou
The following ad runs every week in the local ag paper here: "1000+ 3"x40' irrigation pipe $29/joint with gaskets and good sprinklers. Pipe located in California, delivered anywhere. Brownfield, TX 8
What I do to get accurate layout the easy way is to use TWO tape measures simultaneously, with the zero ends of the tape measures going to existing points, and the far ends crossing over at the right
I poured two bases for MA-550 poles, which have 4 bolts, in a square about 6 inches on a side. In both cases, the J-bolts migrated inward about 1/16 to 1/8 of an inch, despite having them bolted to a
I have built many 1/2 wave verticals and also zepps. It is not clear from your ASCII schematic if you are showing the coil going to ground, but IMHO it should NOT go to ground. The circuit values for
Another reason to have a wire around the rotor bearings is TVI. I had a severe case of TVI that went away when I added a bypass wire. Rick Karlquist N6RK richard@karlquist.com www.n6rk.com www.karlq
I bought some bury-flex and the velocity factor was out of spec (they claim 85%; it was less than 80%). They sent me some more, and it was still out of spec. I see that the link you posted still clai
While we are on the subject: Why is it that M2 uses 5 elements on 20 meters to get 8.1 dB gain but uses only 4 elements on 10 meters to get 8.0 dB gain? The booms are almost the same length, after yo
I have an MA-550 and asked the president of US Tower about the cabling issue. He says they will work with you over the phone and explain the cabling. He told me that the MA-550 is just about obvious
I wanted to EXACTLY measure the frequency of verticals. What I did was to build a very simple noise bridge with only an adjustable resistor, but without the adjustable capacitor (and its fixed mate o
The whole idea of a handheld instrument is that you can climb the tower and measure directly at the antenna. If you want to stand on the ground, and measure through a line, you can use laboratory tes
I'll believe your test, but a better test is a simple dipole against a simple vertical. That way, implementation problems of the 4-square and Yagi don't confuse the results. This must vary with locat
I compared a 90 foot high inverted vee on 20 meters to a ground mounted vertical. About 3/4 of the time, they were too close to tell apart. The rest of the time, the vee was a few dB better. One time
Here is some more food for thought w.r.t. modeling of ground by NEC. I got interested in NVIS by the recent article in QST. I put up five 40 meter antennas to check this out: a ground mounted vertica
There are parallel 16 AWG tinned wires running north-south every 3 feet. There are similar wires running east-west. The wires are laying on the ground. The crossovers are silver soldered with Stay-Br
This is from the 3rd edition (1972) of the ARRL VHF Manual, p198-9: Developed by W1FVY and W1IJD Consists of 3 elements, each element made of 1 wavelength of wire. The elements are formed into (non-c