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[KW4CQ]

I've had two of these up over the past ten years I purchased from different on-line sellers.  While they do perform very well, especially on 20m, keeping them up has been difficult.  They always seem to break where two of the coax cable sections join together.  Those connections are nothing more than a soldered joint between the two center conductors of the coax cables used.  The joint is covered with shrink tubing, which does nothing to prevent breakage.  I hang them somewhat less than flat top so as to lessen stress on the joints but eventually they break.  Has anyone looked at this situation and come up with a better method of acheiving a stronger joint?

[WB6BYU]

Solder joints in stranded wire tend to be problematic if there
is any flexing.  That's because the solder flows up the strands
to different amounts, which tends to focus the flexing on one
or two strands at a time.  That breaks them much more quickly
than when the flexing is distributed across all the strands.

The solution is to make the joint more solid so any flexing
happens outside the soldered area.  Something like a Western
Union splice, with just the center soldered, may help. 
Otherwise, putting some sort of tubing over the joint, perhaps
several layers of shrink wrap, or crimping a copper tube over
the solder joint, may be needed.

My general approach is, "don't put mechanical stress on an
electrical connection".  If I have to make a joint in a wire antenna,
I secure the two wires together (by attaching them to an
insulator, or just tying the wires together if they are flexible
enough) with long enough ends that I can then make the
electrical connection between the free ends.  That way there is
no stress on the joint itself.

If you are using the center conductor of RG-58 coax, or other
relatively small wires, the insulation may provide a significant
amount of the mechanical strength.  That's why I tie the insulated
parts together, then connect the bare ends.

[WA3SKN]

Its not a very strong antenna. Weak link is the coax.  And increasing the coax size increases the weight which increases the sag... etc.
Are you locked into this antenna design?

-Mike.

[W1VT]

I've used crimp connectors that have held up much better than solder joints.
I also use insulators to take the stress off solder joints.  I've also used adhesive lined shrink tubing that bonds better to the wire insulation.

[W6MK]

Lots of good ideas about mechanical/electrical joint redesign of the antenna.

I have always been careful about constructing such joins in my antennas and they never fail there, or fail structually at all. Of course we don't have such things as freezing rain or frequent high winds out here in paradise.

With regard to the W5GI commercial designs, I think they could be modified and strengthened very simply by using a rectangular piece of plastic or wood where the coax joins occur. Drill perhaps half a dozen holes in the rectangle and bind the
coax on both sides of the join to the rectangle using plastic ties. This should take all stress off the joins and the antenna should last a long time.

[KW4CQ]

Good ideas here and thanks. Since I would like to get this particular antenna up and working for me again a couple of ideas just came to mind.  Is there any sort of PVC or Polyethelyne flexible tubing that could be cut to fit over the soldered joint connection, say 6 or 8 inches long, and glued to the outter jacket of the coax?  Some type of cement that would provide a very strong bond.
Alternatively, perhaps a short piece of PVC pipe, with a small enough inside diameter to accomplish the same thing?

[W6MK]

Is there any sort of PVC or Polyethelyne flexible tubing that could be cut to fit over the soldered joint connection, say 6 or 8 inches long, and glued to the outter jacket of the coax? 

Alternatively, perhaps a short piece of PVC pipe, with a small enough inside diameter to accomplish the same thing?

Now you are thinking!

There is heat-shrink tubing that has a strong adhesive inside which is activated by heat. A couple (or three) layers of this tubing should greatly reinforce the coax join.

Yes a piece of PVC pipe should also work. It need not have a small inside diameter to provide a friction fit. Just drill holes at each end and use plastic (UV resistant) ties through the holes to fasten to the coax.