Saturday, March 26, 2016

30m Delta Loop For Heard Island #290

VK0EK has been working 30m almost round the clock on 30m - I need an antenna for 30m with gain over my vertical. My vertical with the ground radials was at best 0.69 dBi based on my EZNEC models

I took down the 160m inverted L - thinking I would put up my 80m inverted L which also works on 30m.  Then I got to thinking, a 30m delta loop has gain on a dipole, 0.65 dBd - to be exact in free space and  -  if I put it up 70 feet, I can squeeze out as much of that 0.65 dB over a dipole..  I also get a quieter antenna so the signal to noise ratio is better.  My friend Matt - took on a different tact and fed it at the corner to have a vertically polarized pattern and to get a lower angle of radiation.  He was saying that he saw 3 S units improvement over his 80m inverted L.   It took a little work to put up the new antenna since I had to shoot up a new line into the tree. The pneumatic launcher came into play.  First I used the Chinese made string spools from eBay - that was a piece of crap - broke the string as the weighted tennis ball arched 20 feet over the 100 foot tall tree.  So I threw all 4 spools into the trash.   I went to my old reliable - 30 lb nylon line wound on a PVC coupler at the muzzle of the launcher and it worked like a charm.   This time I shot way up on a high branch.  My 165 feet of rope was not enough to make a full loop so it is at least 80 feet high.  I added another 20 feet of rope to make a continuous loop.  I did not have a 4:1 balun so I just matched it with the tuner.  The match SWR was 2:1 out of the box so it was an easy match for the tuner.  The delta loop was calculated to be 97.2 feet long forming a continuous loop and feeding at the center of the horizontal leg to polarize it horizontally.  I was probably able to get the apex as high as about 65 feet or so.

They say the proof is in the pudding.  I started calling when a VE and a US station was answering 599. I could hear VK0EK just above the noise floor saying NY4G NY4G 599 a few times - plus their new live web site confirmed it - 00:38 UTC logged Heard Island for #290.

Similarly, friends Paul W4FC and George W4BUW put up a 30m dipole just for grins.   Both of these guys are on the honor roll, so they don't need VK0EK for an ATNO.  They were also able to work the DXpediton on the dipole they erected.

In any event, time for a new stick pin on the map.

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