ultravista
Member
- Joined
- Sep 19, 2012
- Messages
- 99
I am using 24 gauge cross-connect wire (single pair) for my random length long wire antenna coupled to a Nooelec 9:1 balun.
In it's previous version, the wire ran vertical approximately 30 feet - the first 20 feet of the mast being galvanized fence post and the final 10 feet PVC. The wire ran through a metal loop at the top of the PVC down to a point in the yard, then across a cinder block fence to the end of the wire.
The wire was not tethered to the mast but hung loose up to the tip. It was not touching the galvanized pipe.
With a single wire connected to the balun, SW was pretty good and broadcast AM was attenuated well but was noisy. With both wires connected to the balun, one to each post, the noise dissipated drastically as did the SW signal.
I left it with one wire connected for some time.
Yesterday I replaced the PVC with a 13 foot fiberglass telescoping pole (Black Widow Crappie pole). While at it, I secured the wire in several places up the galvanized and fiberglass poles.
To my amazement, with a single wire attached to the balun, broadcast AM was everywhere. The entire SW/HF band was polluted with BC AM signals. No shortwave was possible as the overload was overbearing.
With the second wire attached, BCAM overload practically disappeared, but as it was before, so did most of the noise and signal.
I was not able to pull in any SW stations during times when I would normally. One wire on = terrible overload. Two wires on = no overload but also little signal. I was able to hear an 80M conversation between two hams in Southern Utah (about 120 miles from me) - that's it.
The only real change to the antenna system was replacing the PVC with fiberglass, adding a foot or two to the height, and securing the 24 gauge coated wire to the galvanized pipe and fiberglass pole.
I will check today, but I think the wire running up the pole is perhaps causing the problem. It is secured several times up the pole with Velcro.
If this is plausible, why would the 20 foot section of pipe create such an overload with the wire secured to it? Again, with it hanging loose and not touching, the problem was not present.
I am trying to understand what is happening to have a better understanding of the interplay and ways to prevent it from occurring.
In it's previous version, the wire ran vertical approximately 30 feet - the first 20 feet of the mast being galvanized fence post and the final 10 feet PVC. The wire ran through a metal loop at the top of the PVC down to a point in the yard, then across a cinder block fence to the end of the wire.
The wire was not tethered to the mast but hung loose up to the tip. It was not touching the galvanized pipe.
With a single wire connected to the balun, SW was pretty good and broadcast AM was attenuated well but was noisy. With both wires connected to the balun, one to each post, the noise dissipated drastically as did the SW signal.
I left it with one wire connected for some time.
Yesterday I replaced the PVC with a 13 foot fiberglass telescoping pole (Black Widow Crappie pole). While at it, I secured the wire in several places up the galvanized and fiberglass poles.
To my amazement, with a single wire attached to the balun, broadcast AM was everywhere. The entire SW/HF band was polluted with BC AM signals. No shortwave was possible as the overload was overbearing.
With the second wire attached, BCAM overload practically disappeared, but as it was before, so did most of the noise and signal.
I was not able to pull in any SW stations during times when I would normally. One wire on = terrible overload. Two wires on = no overload but also little signal. I was able to hear an 80M conversation between two hams in Southern Utah (about 120 miles from me) - that's it.
The only real change to the antenna system was replacing the PVC with fiberglass, adding a foot or two to the height, and securing the 24 gauge coated wire to the galvanized pipe and fiberglass pole.
I will check today, but I think the wire running up the pole is perhaps causing the problem. It is secured several times up the pole with Velcro.
If this is plausible, why would the 20 foot section of pipe create such an overload with the wire secured to it? Again, with it hanging loose and not touching, the problem was not present.
I am trying to understand what is happening to have a better understanding of the interplay and ways to prevent it from occurring.
