Have been diligently digging thru the threads and numerous answers abound. So I want to do it right. I am putting up a Sirio sy-4 element Yagi on my CB Base. It will be 43 feet up from highest point of ground level. 1)Reading so many ways of shielding coax cable do I just wire tie it to the mast, as some suggest run it thru conduit standing off from the mast,thru pvc the same way or make a few spins around the mast on the way down. 2) Do I ground the antenna separate from the mast ground, just the mast, isolate the antenna from the mast with plastic/rubber, or some other insulator. I have 3 ground rods close to the mast pole 8ft long driven into the ground. Also have 2 8ft rebar on a 45 degree slant driven into the ground at bottom of mast and welded to it along with a 4ft piece driven in opposite direction 45 degrees and welded to the mast. 3) there will also be a rotor on the mast and do I ground that separate or along with the other ground wires. Like I said I only want to do it once and do it right so you guys know way more than I do from my last venture in 1974 with a simple radio shack ground plane I put on a windmill.
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4 element Yagi going up and want to do it right the first time
- Thread starter 856MD
- Start date
Would have thought that you would be more concerned about the rotor you've chosen.
What are you using?
Just put up the beam according to the instruction sheet. Mount it on a steel pipe, you don't want to use PVC as it will break. Don't worry about routing the coax through the mast; it isn't necessary. Since the beam will be rotated, keep enough coax slack to allow it to make a full turn. Might want to use RG-213, as it is fairly flexible, relatively inexpensive, and has low loss.
The horizontal beam elements do not react to vertical parts of the mounting; so don't worry about it.
Don't ground the beam; ground the mast.
Dunno how you were able to get it 43 feet up with a mast. You must guy rope (not 'guy wire!) it every ten feet to keep that stable in winds - or else it will crumple and fall.
What are you using?
Just put up the beam according to the instruction sheet. Mount it on a steel pipe, you don't want to use PVC as it will break. Don't worry about routing the coax through the mast; it isn't necessary. Since the beam will be rotated, keep enough coax slack to allow it to make a full turn. Might want to use RG-213, as it is fairly flexible, relatively inexpensive, and has low loss.
The horizontal beam elements do not react to vertical parts of the mounting; so don't worry about it.
Don't ground the beam; ground the mast.
Dunno how you were able to get it 43 feet up with a mast. You must guy rope (not 'guy wire!) it every ten feet to keep that stable in winds - or else it will crumple and fall.
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No don't insulate the yagi from the mast, not necessary the whole ant is dc grounded. Sounds like you have the mast well grounded ,make sure all the grounds are connected together to avoid ground loops. The coax will be ok tied down the mast ,put it in conduit if you really feel the need .Tune the Yagi on a short mast first ,I use a 10 ft section mounted on my fence, and expect some change when raised( usually goes up 200 to 300 kc)Another method is to prop the yagi up with the reflector off the ground directors facing up and adjust ( again tune may change when raised to final height).Of course if you can adjust the gamma match easily when mounted thats the way to go .
The first section of the mast is up. It is concreted into the gound (2" schedule 40) and the next section will bring me even to the roofline and then telescope up from there so will mount the antenna when it is at roof level and do all the testing there. At this point I can attach the rotor also. Want to be able to raise and lower it if a hurricane or tornado is called for. My plans are to use a telescoping mast but also I will be putting 3 rods evenly spaced on each section of althread to tighten up any wobble they may cause and also rope tie it at full extended position and halfway down. Want a good stable mast that didn't cost too much and was telescoping. As I have acces to the althread free I will be putting them on each section as picturing a hydraulic cylinder with the rods on the corners. Thanks for the replies on the grounding. I think I over grounded my A-99 more than I needed to even though you can't have enough ground.
You can't have enough grounding as far as lightning is concerned - true. But you will need copper strapping from the bottom of the mast to your ground rods to make that effective. Says nothing about isolating the coax; that is another can of worms.Guy rope the mast from the base of the rotor and every ten feet below that point. I use a telescopic 31 ft mast to the rotor; then use a 5 foot metal mast from the rotor to the beam. The antenna weighs approx 13 lbs and the rotor wieghs about the same or more. That is more/less 30 lbs suspended from the top of the mast, not including the weight of the coax. So it will be top heavy. Add wind force, and it can easily become unstable. Guy it well; just a FYI from a guy who had one crash and burn . . .
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Using #0 guage copper stranded wire right now on the other mast. Will be guying it well and the all thread with nut and shakeproof top and bottom of the rings should each section of mast a little more for less rocking of it since it is only locked with minor clamps. The mast is running up the side of the house and braced in two places along the height. That and the mount pole concreted into the ground will keep that part stable so basically will only be 23 feet above the roof/20 down the side of the house. Thanks for the input. The lightning arrestor hookups on the antenna just dont seem to have the umph by looking at them and the small eyelet crimp connector seems a little shy. I wanted to put my A-99 above the yagi but in reading they say should be 12 feet higher than the beam and dont like the idea of all that top heavy weight added on. Thanks for replying on this
That is a boom truss. Generally not needed unless the boom is small or really long or subject to heavy ice conditions. Some antennas have lateral trusses as well to handle wind better.One antenna I have has a truss for the driver element as it is 42 feet long and has heavy traps on it. I am going to install lateral trusses on it to allow it to handle stronger winds without breaking.
Not wire; but dacron rope. Had some leftover so I thought I would put it to good use. Not that we get ice here, did it just to take the sag out of the boom.
Hey Robb, how come you wouldn't run a ground wire from one of the u clamps where the beam connects to the mast pipe and take it down to the ground ?
Because it would be redundant; wouldn't it?
Another thing about tuning the beam's gamma match. I did it on the ground before I mounted it on the mast. Took a spare 10 ft mast and mounted it to the beam, then I set the beam pointing upward setting it on its reflector. The mast was supported and clamped to a fence so it would keep still.. This made it easy to set the gamma match. Then I put it on the rotor and finished the install. X=2 @ 27.540mhz. Piece of cake.
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That is where the antenna has its best resonance; not where I operate it.ohhhhhh nooooooo,........ the kilocycle cops are gonna get ya
Getting ahead of yourself there . . .
thats what I thot,.......
I was pretty sure you didn't want any OOB issues from a secret "admirer"