On Sat, 20 Nov 1999 13:38:56 -0000 "c penna" <clive@gm3poi.prestel.co.uk> writes: I I had the same thing happen to me. I had 3 el beams for 10, 15, 20 on a 10 foot mast. I thought everything was fine
I think the point that some people may be missing is that "projected area" of a piece of tubing is equal to diameter times length. For example, a 1" O.D. piece of tubing, 120 inches long, has a proje
It doesn't have to go down the exact middle, as long as the hanging point and the bullseye are consistent. You could even run it spaced a few inches outside the tower. Dave Hachadorian, K6LL Yuma, AZ
Not really. turn radius x wt = effective moment c31xr 23.8 x 82 = 1952 ef240 25.1 x 38 = 954 mast 0.083 x 140 = 12 total effective moment = 2918 ft pounds. The t2x is rated for 3400 ft-lbs, so you ar
If the C3 is your only antenna for 10, 15, and 20, I think 75' and 87' are both too high. You might think about adding a second C3 later, about 30' - 35' below the top one. Depending on how your guys
I asked the same question about a year ago, and below are excerpts from two messages on the subject. Cushcraft does NOT recommend disassembly of the traps, so the best way is to use the dip meter. Yo
Another potential problem that can occur when close-stacking a 2 el 40 is that the unused feedline dangling off the 40m driven element can cause that element to become near-resonant on one of the tri
I've done the analysis between 50', 70', and 90' several times, using computer models, trying to decide whether it's worth the investment for me. The difference between 50' and 70' is 2 dB at the use
Rohn drawing B841300, near the back of the book, says "The portion of the steel anchors, from top of anchor block to ground level, shall be coated with Bitumen." I think they mean that gooey black ta
Since horizontal distance is 80% of height, the answer is .8x7 = 5.6 feet. I'm not a soils expert, but 3 feet doesn't sound like enough. You could also back-guy the I-beam like the power companies do
Perhaps you are thinking of a thread (no pun intended) that I started regarding the screws which hold the two halves of the HAM-M thru HAM-IV series rotors together. These are NOT the screws that sec
Another option is to put the top tribander AND the 40 dipole at 85', with the dipole parallel to the tribander boom. The 20' tribander boom shouldn't affect the dipole, especially if the tribander el
If you search the Towertalk archives, you will find a very nice article on gamma-matching the boom of a tribander for use on 40 meters. Apparently it works quite well. Dave Hachadorian, K6LL San Dieg
The Rohn manual is about the best there is. There are so many variations in tower configurations that it always seems to come down to a table of some sort. This reflector is a good way to get the tab
Don't forget to double the benefit if any change helps also on RECEIVE. Multiply the benefit by X if the change helps on X number of bands. Transmit benefit only. Rx is atmospheric noise limited. I t
On Sun, 22 Aug 1999 19:29:29 -0700 "Rod Brink" <rodbrink@montereybay.com> writes: The program YTAD, which will provide a specific answer to this question for your particular terrain, is available fre
I have a similar setup, a big KLM tribander just above the thrust bearing, and a 40-2CD Cushcraft short 40 just 6 feet above the tribander. The booms are in-line, not rotated 90 degrees, and everythi
Harbor Freight has a laser pointer for $5.99 that they say will project a 1/4 inch dot at 600 feet. So you make a little jig to set this thing pointing vertically at the base of the tower in the exac
Wayne Overbeck, N6NB, ran a series of comparison tests on various yagis vs. quads many years ago. The results were published in a national ham radio magazine, "Ham Radio," I believe. One of the findi
The Hy-Gain TH-2 is another small antenna that performs very well. As I remember N6NB's antenna gain measurements many years ago, the TH-2 was used as a reference and had surprising gain for an anten