Old antennas can be aggrevating, but with the cost of new antennas, it is hard to put of a decent antenna farm without reconditioning some older antennas. I really have only owned two brand new antennas, my first one a Cushcraft ATB-34 when I was first licensed in 1978 (now long gone) and just recently a Cushcraft A3WS in service. But I currently own eight antennas that are 25+ years old. I have refurbed all of them from various states. Here are some reoccuring problems and things that I have done to resolve them in the past. These have worked for me but your milage may vary.
Getting a tight fit between the tubing on the elements:
1. Be sure that the hose clamps are in good shape, if the tightening screw have been turned through (or stripped/busted out) then they should be replaced.
2. Be sure to use the right size clamp, for example don't use a 1 1/4" clamp on a 1/2" tubing. These clamp are preformed to fit certain tubing.
3. Place the clamp about 1/8" from the edge of the joint.
4. Use a rachet to tighten, but be careful not to strip it out. You just can not tighten these clamps well enough with nut driver or plyers, but be careful.
5. You can open up the slotting a bit more, but be careful not to open it to much--I would not do any slot/joint much more than about 1/2" to 3/4" more sloting. If you do this then add another clamp (two clamps) to the this joint might also help keep this joint tight.
6. I have used aluminum pop rivets to help hold contrary joints before--one rivet general does the job. Force 12 used pop rivets on some of their antennas.
a. I would recommend the smallest rivets that you can find.
b. Don't use steel rivets as they will rust and cause a problem down the road. Also there might be an issue with the corrosion of the dissimliar metals. Use Aluminum.
c. Put the clamp on these joint along with the pop rivet. Put your pop rivet on the top portion of the tubing. Try to put the rivet where there is no slotting, being sure that you get through both pieces of tubing.
d. Additionally I have used pop rivets to secure the element to boom hardware on Hy-Gain antennas. I guess that over the years an antenna that is assembled, disassembled, etc seems that the alignment of the hardware does not alway come back to the original assembly points. I have found that because of this the element will not line up with each other and one element will be crooked. Tightening the boom to element hardware just seems to pull the element further out of alignment. So I have found that putting a pop rivet through the element to boom plate hardware with keep it in place so that it can tighten the nuts and bolts and keep the element lined up with the other elements. It really probably does make an differenece, but it does drive me crazy sometime. hi
7. My last suggestion for contrary joints would be to put a small bolt and self-locking nut throught the unslotted portion of the joint. Be sure that you don't overtighten this assembly, because if will be easy to colapse this tubing with a bolt and nut. M2 has used this method for year on their antennas in the past.
Final note, once you think the joint is tight, check it with your hands and if you can still turn the joining tubing, it AIN'T tight enough yet...hi hi.
The Wiregrass ARC recently acquired a damaged Mosely TA33JR.
At the local lunch on Friday, there was some discussion about how the trap was made and this picture shows how Mosely does it. There are two coils and the outer sleeve serve as the capacitor for the Mosely Antennas.
You can't tell from the photo but one side of the wire from each coil form attaches to the outside cover.
From the photo you can see that on the left is a brown form and a white form on the right. Both with aluminum windings to create the coil for the tuned circuit for the appropriate bands.
The brown form had the tubing bent a bit, but I was able to straighten it. I basically put the portion that came out of the coil in the vise and slow push it straight. I kept moving the position of the tubing out toward the middle and was able to straighten it pretty well. It was not prefect, but the RF will not know the difference.
The white one had the broken element on the right side of the trap. My initial attempt to get the remaining piece of tubing removed from the white form was pretty ginger because that aluminum wire used for the windings is pretty small and and slightly damaged, I was afraid it would break. So I was not successful in getting the tubing removed.
When the antenna was damaged, it bent in the outside sleeve that covers the two forms. So I had to take the hacksaw and carefully cut the tubing until I could get the white form to pass through that end. I initially used some electrical tape to cover the cut in the sleeve. I think that I will try to get some of the shrink tubing with the sealer and cover this portion before it goes up at the club station.
Actually this antenna was not in that bad of shape.
I have a friend at Mosely, so I talked with him about the cost to just buy a replacement trap and the white form with tubing inserted. Although I did buy some missing parts, unfortunately the cost for a new coil form was prohibited.
So I cut off the end of the broken piece to clean and square up the edge of the remaining tubing. Put a smaller piece of tubing (3/8') through the existing tube as an internal sleeve, pop rivited it to the existing portion and then another piece of 1/2" to the appropriate length over the top of that sleeve and pop riveted it in place. It was a clean repair and the trap end cap covered the repair.
Another problem that developed with this coil was the end of the coil itself comes out past the sleeve and attaches with a screw. Unfortunately during the process of working with it the loop end broke off. I found that the coil was very tightly wound on the form and began to unravel so I put a ty-wrap on it to keep it from undoing completely. After talking with Aaron/KF4BHP he suggested that I just notch the form in a different place, create the loop and then attach it with the screw--it worked perfectly. It would shorten the coil a bit, probably about 1/2". It really had no impact on the performace of the antenna.
So here is a picture of the completed antenna as we used it during Field Day 2012. Well I got a little stupid with the assembly on Saturday and got some of the elements mixed up, but once we sorted that out the antenna played very well. Well enough to produce a 105/hour on Sunday morning. hi