The 40Mhz IR2030 WSPR beacon has been active constantly since 1000hrs on Saturday 20/11/2022 my thoughts are now turning to carrying out local reception plots around the area.
At 10mW's ERP from the halo in the loft, I'm wondering how far this will go ? 10metres, 500metres 1Km...at a rough guess I'm saying a kilometre as the receive antenna isn't going to be a small coiled up whip like you would get on a remote controlled cars. The receive antenna does have me stumped though and stringing up a halfwave dipole each time on site isn't practical, it needs to compact, portable and easy to set up and dismantle.
I want to gather enough information as possible at the different sites, so thinking I really need two antennas vertical and horizontal to give a fair test on any variables.
Not that long ago I bought a 9ft tank style CB whip with a 3/8 thread that comes in two parts. I was going to use for my 28MHz WSPR-AXE-CW beacon but in the end I decided on a endfed wire so the whip is now spare. As I don't want to cut the top section of the whip down I was lucky to have found other sections of thin whips from other antennas in the past and used one of those to make a 1/4wave whip.
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| Modified CB whip for 40Mhz |
That's the vertical sorted so what about the horizontal antenna? I've always enjoyed watching Peter VK3YE youtube channel, he comes up with some really interesting pieces of equipment and one of many items I've reproduced of his was the Summertime loop II . I built it quite a few years ago and never really got round to finishing it off with a mount/handle.
It covers 20M to 6M using a beehive trimmer, tuning is fiddly and moving the antenna about the SWR does alter abit. A quick test and I was able to get a reasonable match on 40.680MHz, the good thing is I can rotate the loop were necessary on site. Having a quick look over it I need to clean the contacts and make some form of handle/mount to hold it too. I would like to get rid of the beehive for a fixed capacitor but if I have value(s) is another matter.
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| My Summertime loop II on 40.680Mhz |
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| Under 1.5 at 40.680MHz |
Good luck with those tests Jason. This is REAL research.
ReplyDeleteYou could use a piece of coax as a fixed capacitor. Cut it until resonance is achieved. You will probably cut off too much. If this happens, you know the length you need!
ReplyDeleteGood luck with your tests Jason, look forward to reading your results. I know Hugh in Portugal has been monitoring WSPR as well FT8 so if there's some Es about you may even make that trip.
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Paul G9PUV