Finally fixed (but knock on wood) REVISITED

On December 21, 2008 I thought I fixed the 80/160m antenna. Hence my Finally fixed (but knock on wood) posting that day. And yes it got fixed. And yes it worked. But as you know it didn’t work anymore when reinstalling after the Great Summer Takedown. With 160m and contest season almost here, it was time for affirmative action. I did some nightly thinking, reading and surfing that resulted in a posting on the Top Band reflector (link). A lot of good answers. Coils, relays, loading and traps. Everything that involved loading the 80m antenna to work on 160m, also requires switching the loading in (160m) and out (80m) of the circuit. So that means additional relays, boxes, control cables and interfacing from the shack. So I tried my luck with a trap. I need to make a trap but it ends there. No more relays etc. Because I had visions of burned RG58 or RG59 traps when applying my 900W, I tried to make a trap with some leftover H100 stiff coax wrapped around a piece of PVC tube with 125mm diameter. I put the trap on the inverted L and pulled it up with the rope and pulley. I didn’t even get out the antenna analyzer. This thing is way too heavy and the L wire had too much sag. Note to self: stiff solid dielectric coax is not made to wrap around tubes.

There had been a little flame burning in the back of my head. So I unleashed the carburetor and injected some fuel into the antenna brain. There is another solution. A second antenna. Worth a shot. Luckily I have a big pile (a/k/a the junkyard a/k/a garage) of scrap bits and pieces and leftovers from previous projects. Here’s what I came up with. I took some pieces of 16mm PVC electrical conduit about 30-40cm long. I drilled holes through those and used them as spreaders. That created two parallel wires sharing a common antenna feed point. They go up the tower (with pulley and rope) and up the tower they split ways. The 160m L goes to the left and the 80m L goes to the right. For testing purposes the tower is only 2/3 up. For contesting both tower sections will be cranked up so the 80m vertical will be full size and the 160m L wire will be approximately 50/50 vertical/horizontal.

Sure enough the antenna analyzer showed two nice dips. In the shack I found that the MFJ tuner accepted the impedances and took 900W on both bands. That’s the good news. Now the better news: with some pruning I think I can get both bands to work WITHOUT the MFJ-998. That would be super. However I now have a working concept. A simple concept. No coils, no traps to burn, no relays to arc. And most of all no big stack of ferrite cores to heat up. The only ferrite is a big long custom made DX-Wire coax choke balun with 80 beads. All that I need to do now is make some temporary things more permanent. Then add some more radials.

To test the antenna last night I worked a new one on 160m first call right through the pile up. The DX was OY3AA. Hey, new DX is new DX! As it turned out later I already worked an OY in 2004 but never received a QSL for that 160m QSO. I know that OY3AA uploads to LotW pretty fast so there you go. DXCC counter on 160m +1. This morning I heard a K9 about S5 strong with some QSB but he didn’t hear me. Rather: he heard me but didn’t copy. Then I heard a loud GI3 work KH7C. But no trace of Hawaii on my antenna. The contrary would have surprised me.

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