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Old 8th Nov 2019, 5:30 am   #1
vu2nan-nandu
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Default 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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Old 8th Nov 2019, 12:22 pm   #2
Dave757
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Default 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
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Old 8th Nov 2019, 7:11 pm   #3
vu2nan-nandu
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Default Re: Makeshift Square Loop Antenna for a Crystal Radio

That's a great idea OM Dave!

Many thanks.

73,

Nandu.
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Old 9th Nov 2019, 12:51 am   #4
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Default Re: Makeshift Square Loop Antenna for a Crystal Radio

Quote:
Originally Posted by Dave757 View Post
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.
Unless your wardrobes have sliding doors
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Old 9th Nov 2019, 5:35 am   #5
vu2nan-nandu
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Default Re: Makeshift Square Loop Antenna for a Crystal Radio

Yes, of course, OM Terry .

73,

Nandu.
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Old 10th Nov 2019, 12:57 pm   #6
julie_m
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Default Re: Makeshift Square Loop Antenna for a Crystal Radio

Quote:
Originally Posted by vu2nan-nandu View Post
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.
Broadside on, surely?
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Old 10th Nov 2019, 4:41 pm   #7
Dave757
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Default Re: Makeshift Square Loop Antenna for a Crystal Radio

Quote:
Originally Posted by julie_m;11904unit.[/QUOTE
Broadside on, surely?
Hi Julie,

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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Old 10th Nov 2019, 7:26 pm   #8
vu2nan-nandu
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Default Re: Makeshift Square Loop Antenna for a Crystal Radio

Thank you for the explanation, Dave.

Regards,

Nandu.
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Old 11th Nov 2019, 12:31 pm   #9
Karen O
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Default 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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Old 12th Nov 2019, 1:56 pm   #10
vu2nan-nandu
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Default 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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