| Tuesday, April 01, 2008
| Delta Loops and DX QSOs
|There have been some signs of improvement with regular openings on HF most days here at My Q T H.
My home brew 20 meter delta Loop has been Performing well since I repositioned it in a Vertical configuration.
DX. Stations are becoming more regular on 20 M especially stateside and the Middle East. 40 M has provided some nice openings into South America as well as Canada. Ive been fairly active lately making the most of the good conditions making many interesting QSO
I’ve also been putting out some good Signals from the mobile making plenty
Of contacts on my favorite band 2OM.
It’s always a Pleasure to work new Stations and especially nice to be able to say a quick hello to a nice group of regular radio amateurs. Like Ivan LZ2LP. Mohamed 7X4AN and Gary EW1MM.
I got the illness us Hams get regularly which was the itch and urge to have a go at another home brew delta loop over the weekend. So with the Sun shining I rounded up some tools and wire which turned out to be 3mm plastic coated copper wire. I decided to have a go at making an antenna that might work on 137MHZ which I would use to receive Weather satellites such as NOOA Satellites which transmit imagery data signals on FM. I’ve had good results in the past using the 2M 7/8 wave vertical, with this in mind the resonant length of wire that I cut was for 2M and luckily the SWR was good across the whole of the 2M band.
I used a formulae I came across on the Internet which is very simple to use, it helps you to work out the total length of wire used to make a closed circuit delta Loop on any band.
Length (Feet ‘)
Example for a 20M Delta Loop like the one that I use.
14.200 MHZ = 70.77
+ the length of wire used to secure and connect to feeder and dipole/loop centre = near enough 71 feet. This should be reasonably resonant if fed with a ¼ wave length of 75ohm coax terminating to 50ohm coax. An ATU is required for other HF bands.
The length of wire I used to build the Delta Loop which was mentioned earlier, was only 6feet 9inches in length to provide a low SWR. I came to this result using the same formulae which again proved accurate
145.000 MHZ = 6.93 = 6feet 9inches which worked out well across 2M as well as 137MHZ-WX-NOOA Signals.
Once I crimped some lug connectors on each end of the wire. I laid the wire out on the floor in a triangle with equal sides, then I positioned the feed point approximately 4inches from one of the bottom corners.
Using cable ties/tie raps I was able to connect each corner to a thin piece of rope. This made the delta loop simple to install in the vertical configuration in the near bye tree outside.
As I was putting the new Loop up I had the FT-857 on 2M SSB 145.200 when an Irish Station started to come through the speaker. Louise my YL and HAM (M3TLL) came rushing outside to tell me the news. I followed him and another Station that I was not receiving down to the frequency they were using.I was receiving the Irish Station S-2, Q-5. I headed outside again and installed the loop vertically in the tree using the rope and cable ties. The Irish Stations signal was now up to 5/7 so I was extremely surprised on how well it was working.
I have made a couple of contacts on 2M with reasonable results and I have managed some quality images of the earth via the NOOA Satellites that I’ve managed to receive. I am still in TEST mode for a while before I can really provide accurate feedback, but so far so good.
As far as HF goes the 20M Loop, the 6BTV Hustler and G5RV have received and transmitted some distant signals, with a new DX Country ‘JAMAICA’ added to the collection last Friday night on 40M. I had a lucky break when I got in early during the pile that was about to happen when 6Y1V was 5/9 both ways during the speedy contact we made-Very nice!
Last night was also good especially 20M as I was hearing Mexico and The Caribbean coming through 5/7+.
Hopefully the new cycle will bring even more rare and distant signals to be heard at The 2E0HTS Home or Mobile HAM Station.
73 all the best DX
De 2E0HTS Simon
|posted by Simon Davison @ 6:08 pm