My tower is near the center of a small lot, 60 by 120 ft (18 by 36 m). When I decided to shunt feed the tower on 80 and 160 years ago, I initially put in 13 crooked buried radials, largely based on O
Hi Matt, Your calculations are correct, but the only reason the thrust bearing in your example reduces the bending moment on the mast is because it is 2 feet above the rotator, shortening the length
I agree that the resistance of the thrust bearing to bending can affect the moment on the mast. However, the moment just above the bearing is not affected, and can be easily calculated. I think this
Yes, once you get into an overconstrained configuration and have to consider the stiffness of all the components, things get a lot more complicated. I expect mechanical designers now use finite eleme
OK, technically the Rohn TB3 is a radial support bearing, with vertical races. That's just not what Rohn calls it. 73, Scott K9MA On 12/26/2020 12:34 PM, Wilson Lamb wrote: Why can't we get the termi
Here is the DXeng "advanced thrust bearing" cross section. Click to last cross section picture. https://www.dxengineering.com/parts/dxe-tb-300 Definitely a better design than the Rohn TB3, and only a
Right. When I tried to lower my old mast through the TB3, I found that the boom to mast clam had distorted it enough that it wouldn't fit, making it a lot harder to get the mast down. The new one wen
I don't think so, unless you are using some sort of noise cancellation with two antennas etc. Noise blankers can be very effective against impulse noise, typical of line noise. However, they don't wo
Noise from electronic devices can have that impulse nature, for which noise blankers are effective. The AM audio often has harmonics of 60 and/or 120 Hz, as does that of power line noise. Most often,
When I put my tower up in 1989, my next door neighbor raised a ruckus, because she thought it would hurt her property's value. After the house was sold some years later, I asked my new neighbor if th
The late W0AIH used to splice hard line by bending the two ends upwards, connecting the shields and center conductors, and slipping a plastic soda bottle over the whole thing. Ugly, but cheap. 73, S
I had one neighbor, who never identified herself, threaten to "shoot my tower down", because her telephone was a good receiver. That was long ago, and she's long gone. I've had no complaints in many
I only wish I had less experience tracking down RFI. At least here in the city, dogs and guns aren't a great hazard. I do wish, however, that my utility was as responsive as Ignacy's. 73, Scott K9MA
Keep in mind that, unless the tower is very stiff, the horizontal component of the tension in all the guy wires will be equal. That means that if the anchor points are not equidistant from the tower,
-- Scott Ellington -- via iPad It wont necessarily be plumb, be at least it will be stationary! 73, Scott K9MA _______________________________________________ ________________________________________
I've long believed that just about every fastener in an antenna system should have Loctite on the threads. How many neglected tribanders have you seen with elements askew? That won't happen if there'
I recall from my space hardware days that all the connector pins were crimped. The crimp tools had to be regularly calibrated, and periodically a pull test performed. Crimped connections can be very
There are all sorts of metal and fiberglass telescoping poles available. With guys, you really don't need much of a base. Carbon fiber is overkill if weight isn't a big consideration. Guys can be Da
A friend in New Zealand, now SK, had built a tilt-over mast perhaps 40 feet tall out of 3 pieces of tubing. Sort of an overgrown version of the wooden one that used to be in the old Handbooks. I'd im
If you're willing to spend the money, Spiderbeam has fiberglass poles up to 85 feet. 73, Scott K9MA Since you indicated guys were not a problem, you might want to check out the telescoping masts that