"Thomas" wrote in message
...
I have taken two lengths of 1.66" OD (1-1/4" nominally labeled) PVC pipe
("top" is 5 feet long, "bottom" is 10 feet long) and connected them with
a PVC "T" joint.

On the top I have wound 210" long 12 gauge, solid copper wire to cover
about 4.75 feet of the "top" PVC length and done the same on the "bottom".

I feed a length of RG-8 into the bottom of the pipe and out the "T"
joint and connect the center conductor to the top winding and the braid
to the bottom winding.

The whole smash is then mounted vertically in an old umbrella stand.

So I have a vertical dipole with roughly lambda / 4 (for 20m) length of
radiator top and bottom. I was not sure whether to wind the top and
bottom the same way so I "matched" them insofar as they look like the
continuous threads of a screw. Not sure if that is right.

Seems to work well as a receiving antenna, not sure on the transmitting
part as yet.

Comments, especially regarding construction changes and tuning would be
welcome.

Thanks.

73s

Thomas

I see 2 problems here Thomas. You are confusing the length of the wire you
wound into inductors as having the same electrical length as a straight
piece- nothing could be further from correct. In fact, the relationship
between the amount of wire in the coils and their equivalent electrical
length is complex and depends on a number of factors including where along
the radiator the inductors are placed.
Secondly, running the coax up inside the PVC will likely result in a large
amount of RF being impressed on the exterior of the coaxial shield.
Visit Reg Edward's site to see how to electrically shorten a radiator with
inductive loading.

Dale W4OP