Loose element walked down the boom.

[Captain Kilowatt]

Well I got a surprise today.I was upstairs in the house and happened to look out the window up at my tower.Much to my surprise I saw the reflector element of my A3 tribander about a foot from the driver element in the middle of the boom. :shock: My first reaction was WTF?? How...?? What...?? Then I saw the element rotate slightly in the wind.The bloody thing had loosened up and in the wind it had worked it's way about 6 or 7 feet along the boom until it rested against the boom splice.SWR is up and F/B is down :evil: Now I have to take it to ground level and tighten things back up.Not real easy due to two more antennas above it and lots of tree branches between it and ground.Also it is now not balanced very well.This time I will make sure and put in a pin to keep that from happening again.Anybody ever have that happen before? I was thinking of rotating the beam and let the wind put it back in place.

 

[2at124]

antenna

it a good idea to put sheet metal screws on any element or if a bracet hold them in place to secrue them to the boom and also if u have a L bracet thet mount the antemnna to the mast it good to put one aswell . I also have them on the bracet the holds the mas in the rotor too in Nj in the winter we bad north east winds so i like to be sure nothing moves . Fixin a antenna in the middle of winter in not fun

 

[Captain Kilowatt]

These elements mount with a kind of saddle bracket with a U-bolt around the boom.There is a set screw in the bottom of the saddle that bites into the boom to keep the element from rotating around the boom.The setscrew must have either loosened or broke.This past winter has been very hard on antennas with several blizzards,one of which actually broke my driver element,and some winds that I have NEVER seen here before.Here in Nova Scotia we see a lot of nor'easters and believe me I know how to mount antennas but in this case something must have let go in the bracket screw.I know what you mean about winter antenna maintenance.I had to repair the broken driver element and put it back up in Dec. when it was just a few degrees above zero farenheit and a breeze blowing.It aint fun 40 feet off the ground in that.

 

[Jay in the Mojave]

Hello QRN:

The A3, 3 element beam, for the director and reflector are mounted on 1 1/2" OD (outside diameter) Aluminum Tubing. A 6 or 8 inch long, 1 3/8 aluminum tubing can be placed inside the 1 1/2 inch boom if its not distorted by over torquing the U-Bolts.

http://www.cushcraft.com/amateur/support/instruction-manuals.htm

This will internally reinfore the boom allowing the U-Bolts to really be tighted down. Many home depot or Lowes Stores carry stainless steel U-Bolts. The extra thickness of the reinforcement 1 3/8 tubing will also allow for a much better grip from a sheet metal screw to go in and stiop the element from rotating and getting loose. By adding the 1 3/8 inch tubing the wall thickness goes from .058 to .116, allowing the boom to be stronger and allow Pop Rivets or sheet metal screws to really get a bit into the Boom, and casing a binding agains the sheet metal screws.

If you need some 1 3/8 OD Aluminum Tubing e-mail me and I can send some pieces your way.

Jay in the Mojave

http:;//www.a1antennas.com

 

[Captain Kilowatt]

Thanks for the offer Jay.It will be a couple weeks likely before I get a chance to get it down and see just what really happened to it.Two years ago I completely rebuilt it with all new stainless clamps,not the cheap ones with the non-stainless screw but complete stainless all the way,and used stainless steel clamps for the boom splices and the element clamps.I even took the traps apart and cleaned them out.I suspect the set screw went south on me.I was thinking about reinforcing the boom at the element mounting points with either smaller tubing or even heavy walled black ABS pipe.I think the end may be slightly crushed so that may be a bit hard to do but I will have to get it on the ground and really give it a good going over because it is a real pig to put up.I have to rotate the elements into the verticle plane to avoid trees branches (lovely oaks I hate to cut back) and then rotate back horz. without getting tangled in my 6m and 2m beams that are mounted above.It is a job but I have it mastered.I even took the 6 element 6m beam down for repairs and put it back up above the A3 without taking the A3 down.I just need the time and weather.Speaking of weather,anybody want some rain? It has been raining here for two solid weeks and the forecast calls for more rain right up to next Tuesday at least.The south east part of the province was under a state of emergency for a couple days due to flooding.They got over 200mm (8 inches) in the last two days alone.If we get much more rain I'll be able to take the beam off the tower with a boat.

 

[Jay in the Mojave]

Hello QRN:

Yeah just let me know. Yeah I had 8 to 10 weeks of rain here and a bunch of projects to finish. Now I am out spraying all the weeds from the all tjhe rain we had.

The ends of the Boom can be cut off where the U-Bolt has left it dented or oval shaped. Then new 1 1/2 tubing can be spliced into the Boom, with 1 1/8 inch installed inside the 1 1/2 tubing, with the ends held tightly end to end, Aluminum Pop Rivets are used hold it all together. So now you would have a new ends and reinforced to allow the element to not move around.

We where running SWR vs where the beam was pointing tests to see what happens with SWR with close installed metal guys wires would effect the Super Crusader 7 element yagu beam antenna. The swr went nutzoid as we found the first director have been blown by high winds right next to the driven element.
I figured that I didn't tighten the first director down tight enought or it was just hand tight?!?!?!?!?......

Jay in the Mojave

 

[Captain Kilowatt]

I know what you mean about the hand tight business.Two years ago I looked out and saw the antenna stack was pointed north-east.I was sure I had left it pointing due north as I had worked a bit of 6m auroura the night before.I checked the rotator display and sure enough it was set at north.I spun the antennas around and everything moved as it should.I thought, great the direction indicating pot has probably gone bad as many have in the Ham series rotators.The next week I was on the air and peaked a signal while turning the beams and thought whoa,this is not right.The beam was side-too the station according to the readout.I had the wife turn the beams while I looked out the window and all looked smooth and fine.Then I started to wonder about the ring gear.I had broken one many years ago and the antenna would windmill some.Eventually over the next week with high winds the beam was exactly 180 degrees off.With a break in the weather I climbed the tower ready to take down the three beams and prepare to have the rotator repaired.I then found out,much to my embarrasment,that I had tightened the three mast clamps on the thrust bearing with a wrench but had tightened the rotator clamps only finger tight the last time I was up the tower.What I do is to set the mast into the rotator leaving about 1/4 inch space from the bottom of the mast and the rotor.I clamp that solid and then clamp the bolts on the thrust bearing.Next I loosen the rotator clamps and then tighten them again as that transfers the weight onto the thrust bearing and leaves no weight on the rotator.I guess I loosened them and forgot to tighten them back up right after.