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8th Nov 2019, 5:30 am | #1 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Makeshift Square Loop Antenna for a Crystal Radio
A heavy 2 m x 2 m floor-standing wooden showcase in the shack appeared to be suitable as a frame for a crystal radio loop antenna. As luck would have it, the lone 20 km distant 612 kHz, 200 kW AM broadcast station being in the end-on position by default, there would be no need to move the unit. The counter top would make it quite convenient to sit down and carry out the testing.
The 5 turn loop was easily wound using about 42 m of ordinary hook-up wire. The shack is relatively quite small to get a photo of the actual unit. A representation of the same is attached. It works quite well with my series/parallel-tuned crystal radios. Further details at https://nandustips.blogspot.com/2019...tal-radio.html 73, Nandu.
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8th Nov 2019, 12:22 pm | #2 |
Heptode
Join Date: Apr 2009
Location: Scratby, Norfolk, UK.
Posts: 648
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Re: Makeshift Square Loop Antenna for a Crystal Radio
Hi Nandu,
You might also try a loop on the back of a large wardrobe door, the main benefit being you can usually turn it through 180 degrees. I use loops here too, as I have no space for outdoor antennas. Kind regards Dave G0ELJ |
8th Nov 2019, 7:11 pm | #3 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Re: Makeshift Square Loop Antenna for a Crystal Radio
That's a great idea OM Dave!
Many thanks. 73, Nandu.
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9th Nov 2019, 12:51 am | #4 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,324
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Re: Makeshift Square Loop Antenna for a Crystal Radio
Unless your wardrobes have sliding doors
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9th Nov 2019, 5:35 am | #5 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Re: Makeshift Square Loop Antenna for a Crystal Radio
Yes, of course, OM Terry .
73, Nandu.
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10th Nov 2019, 12:57 pm | #6 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Makeshift Square Loop Antenna for a Crystal Radio
Broadside on, surely?
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10th Nov 2019, 4:41 pm | #7 | |
Heptode
Join Date: Apr 2009
Location: Scratby, Norfolk, UK.
Posts: 648
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Re: Makeshift Square Loop Antenna for a Crystal Radio
Quote:
If it was broadside on, both sides of the loop would receive the same phase? of the signal simultaneously, and this causes a null in the signal. This is why Direction finding loops are normally turned broadside on to the beacons to obtain a bearing, as the null is very sharp, whereas the maxima 90/270 degrees away are very broad (figure of 8 pattern). Kind regards Dave. |
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10th Nov 2019, 7:26 pm | #8 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Re: Makeshift Square Loop Antenna for a Crystal Radio
Thank you for the explanation, Dave.
Regards, Nandu.
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11th Nov 2019, 12:31 pm | #9 |
Rest in Peace
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
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Re: Makeshift Square Loop Antenna for a Crystal Radio
A good friend of mine has suggested pressing a colour TV degauss coil into service as a loop antenna (extracted from the TV, of course!). I don't know how practical this idea is...
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12th Nov 2019, 1:56 pm | #10 |
Pentode
Join Date: Jul 2014
Location: Bangalore, India
Posts: 132
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Re: Makeshift Square Loop Antenna for a Crystal Radio
Hi Karen,
An old colour TV degauss coil would be about a metre in diameter and have around 50 turns. I guess it would work, with the turns spaced out, at LF / VLF. Regards, Nandu.
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