Yes, rg58 should be about 40pf/ft. just beware, if the length becomes a significant fraction of a wavelength then you have to calculate the impedance based on the length and velocity factor. David Ro
You know I keep reading the stuff on those and this pdf started to make some sense on what the thinking is about those porcupine things. First, they will NOT prevent lightning strikes, that has been
Yeah, capacitance varies. The 40pf/ft was the first one I saw in my belden book, other variations were listed at 28 or 30pf/ft. David Robbins K1TTT e-mail: mailto:k1ttt@arrl.net web: http://wiki.k1tt
So, just how often does a tower get hit... lets look at some statistics and physics. A 40' tower guyed with steel wire may collect lightning strokes from a 100' square area, more or less, but probabl
That is not a good assumption either while the mathematical models may show that taller structures protect shorter ones, lightning is not known to have studied those models very well. Lightning trigg
They won't work either for the same reason as the porcupines don't work. You can not discharge the tower or building to the ground, the charge is coming up from the ground to meet the leader coming d
A label of "JP" on something that looks like a resistor is probably a zero ohm resistor, also known as a "jumper". They actually make those for automatic circuit board stuffing machines where you mig
If you don't have the fancy jack stands the easiest way is to find 2 trees farther apart than the reel width and closer than the longest 2" pipe you can get, use comealongs or just jack it up and tie
Two step ladders work also in a pinch, the wider the base the better. David Robbins K1TTT e-mail: mailto:k1ttt@arrl.net web: http://wiki.k1ttt.net <http://wiki.k1ttt.net/> AR-Cluster node: 145.69MHz
My turnbuckles are all wired. I just take a cut off piece of guy wire and loop it through the bodies of all the turnbuckles and then through the live side eyes, that way neither side can turn. David
That wire wrapped around the butt end of the utility pole is amazingly called a 'butt wrap' and is a common method of installing a ground at the base of a pole, there is no extra hardware, no driving
Lets see-saw... 1. chain saw 2. pole saw 3. saw attached to a drone... (have you seen the video of them trimming trees on a power line right of way from a helicopter? Nasty!) 4. saw(or wire cutter) o
Hmmmm, didn't seem to go the first try... Lets see-saw... 1. chain saw 2. pole saw 3. saw attached to a drone... (have you seen the video of them trimming trees on a power line right of way from a he
Not only is it very slow propagation, but it is very lossy propagation as there are streamers and corona and all sorts of other ugly things going on underground along a radial. When I measured the ve
<The shields of the coax on the tower are bonded and hit the tower's ground system but the center of each coax is left floating. My thinking is that I prefer that suppressor take a hit and try to dum
Or do like I did after burning up several of the M2 Yagi baluns (really just small ferrite binocular chokes)... replace them with coax air core chokes. David Robbins K1TTT e-mail: mailto:k1ttt@arrl.n
reasons I articulated in k9yc.com/RFI-Ham.pdf Air core is better than cracked ferrites and melted coax in those little pvc cans!! And can be done quickly with materials at hand without having to wor
Why must a balun provide isolation? how can a coil of coax be considered a balun as there is no isolation of the currents on the inside of the coax provided like there can be with a transformer. Davi
"The inductance of a coil of coax is in series with the rest of the transmission line, and if that line looks capacitive (by virtue of its length), the coil of coax DOES NOT WORK to provide isolation
Ancient reference for aircore baluns: http://www.k1ttt.net/technote/airbalun.html David Robbins K1TTT e-mail: mailto:k1ttt@arrl.net web: http://wiki.k1ttt.net AR-Cluster node: 145.69MHz or telnet://k