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Post by Deleted on May 17, 2018 22:08:22 GMT
Uses for Radio?This magnificent copper coil is an electromagnet, but could it be used as a loop antenna? Real Center Piece
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Post by mark on May 17, 2018 23:22:32 GMT
It may look similar to the AM loops like this...https://www.universal-radio.com/catalog/portable/0912io.jpg
But this one is for another purpose and would have to have the right amount of turns and tuneable to be an AM antenna with the right frequency range.
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Post by Boomer on May 18, 2018 4:45:00 GMT
There's some mystery in that coil, they don't say what it's for. Ah, from Carl's post, electromagnet. In that case I'd imagine it's too much wire for a coil on the broadcast band, meaning too high of an inductance to resonate.
Usually the 3 meter antenna (you measured the length) needs 300 to 400 microhenries to resonate near the top end of the AM band, that's a good reference to go by.
I like how it looks too, like the Radio Shack AM broadcaster kit I built one time that had a big square coil like that. Metal detector coils can look like that too.
Boomer
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Post by station8 on May 18, 2018 14:40:00 GMT
Howdy y'all: Neat coil!
Keep in mind you need to know your tx output circuit due to NOT one am tx is the same!
Also keep in mind NOT all coils are the same as well!!!!
Also keep in mind each antenna you build is NOT the same as well!
So in the end you guys say 300 to 400 michroheny is which you need for the upper end of am,
Let's sit back and look at this from a perspective view
Well this is a true and false statement due to the building of the
Tx and coil and antenna systems!!
The reason why I say this is to keep confusion out of the subject!
So what do you think place your inputs.
Have fun jeff
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Post by Druid Hills Radio on May 18, 2018 16:36:50 GMT
Howdy y'all: Neat coil! Keep in mind you need to know your tx output circuit due to NOT one am tx is the same! Also keep in mind NOT all coils are the same as well!!!! Also keep in mind each antenna you build is NOT the same as well! So in the end you guys say 300 to 400 michroheny is which you need for the upper end of am, Let's sit back and look at this from a perspective view Well this is a true and false statement due to the building of the Tx and coil and antenna systems!! The reason why I say this is to keep confusion out of the subject! So what do you think place your inputs. Have fun jeff Thanks Jeff. I always look forward to your technical tutelage. |
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Post by Boomer on May 21, 2018 1:55:28 GMT
I'd have my antenna at the top of the coil and feed the transmitter's output between the bottom of the coil and ground, then tune the coil with your capacitor and taps at the antenna side.
If the transmitter is 50 ohms out, feeding between the coil and base can cause a slight mismatch however.
In that case it can be good to ground the coil's base and have an adjustable tap anywhere on the coil between 1-6 turns of the base.
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