89. DIY AM Antenna "Amplifier"

A simple passive AM antenna "amplifier" to pull in those weak stations. Inexpensive and has more sensitivity than many of the commercial models.

[@wojciechbartczak3109]

Your videos are extremely useful. Electronics is partially my education and partially my hobby. Since recently I have no space and/or time, I left only with watching videos. I've watched tons of videos on YT and the whole internet and there aren't a lot of them pack with content like yours. Please don't give up!

[@TheOffsetVolt]

Thank you, I'll try to get some more videos out.

[@aerofart]

You’re a good man, TOV. Thanks for all you do for the community. Your videos are tremendously educational and entertaining.

[@heinerrambold8889]

Loops for the low frequencies are not hard to build. However, with increasing frequency it becomes more and more challenging. Thanks for the video!

[@deltagold9646]

Content is excellent, thank you. After the FM portion of the Elenco is complete, It will be a pleasure to grant your site a donation. Your high level of proficiency is well worth it.

[@TheOffsetVolt]

I appreciate your feedback. I don't know that I could take any contributions from viewers. I feel like I would have to publish more content to make it worth a contributors money. Thanks for watching.

[@Debraj1978]

Lot to learn from your video. I am an electrical engineer, but work on power side. But learning basics is something I love to do all time and your videos are superb.

[@TheOffsetVolt]

I appreciate that. The power side of electronics - the dark side...lol.

[@cerglabs3646]

Great channel! I especially loved the Op Amp series. I learned a ton!

[@TheOffsetVolt]

Glad you enjoyed it!

[@patricklanra3507]

Merci - vos vidéos sont tres interessantes à suivre.

[@satheehkumars2201]

your video is very much usefull to me because I was in problem to get Am sation in my radio. straight away I am going to make one for my use. I will came back to you after I construct the same and use. Thank you very much for your kind information

[@tomdoyle9785]

Excellent content. Great Presentation. Thanks!

[@suhailasaba1051]

4:48 Great video. Thanks for the formula.

[@TheOffsetVolt]

Glad it was helpful!

[@bapibapi7371]

Many many thanks to you for your tutorial videos. I am from india

[@mmallick3224]

Thank you Sir. Your video helped me a lot. Looking forward for some similar informative videos. I'll try my best to build a similar one. I want to build a smaller one, what will be measurements of the side and the number turns of the wire?(I was successful in building a dipole FM Antenna that perfectly catches Stereo signals from 70 miles aways alongwith other physical obstacles).

[@Dad-ij2qy]

As an EE and former extra-rated ham, I thank you for presenting the best presentation yet on a AM LC resonant loop antenna. I appreciate the RC equations as a functions of frequency. So long as you use insulated magnet wire to make the coil, it' shouldn't matter if the coils are right next to each other, so long as the wires don't get hot enough to melt the insulation and short out. I heard other AM broadcast band antenna builders proclaim a 1 foot by 1 foot square for making the loop. Are you sure 2 foot by 2 foot is the right value? I suppose will have to do further research on coil building to determine the inductance of hand-wrapped square loops.. I am hoping to find a source for the variable air capacitor for tuning this magnetic loop antenna. If you know where I can buy one, please post here. I hope to find one, so I don't have to run wire outside my house ( I live in an area where air temperatures drop below freezing for 2 to 3 months of the year), so I don't have to drill a hole in my house to string a grounded antenna outdoors with 50 to 100 feet of wire.

[@morpher44]

for wheeler formula of inductance, you actually want the width of the coil to be greater than .8 x mean-radius, and so a width maybe 10 in or so... with each wire 6 wire distances from each other.

[@tomdoyle9785]

Could this, when adjusted for frequency, be used to increase cell phone signals to rural areas? Thank you

[@arjunprajapati8352]

Thank U Very Much Sir.

[@TheOffsetVolt]

Most welcome

[@williamhazelwood8288]

Good video thanks intresting about using the loop antenna to find the source.

[@TheOffsetVolt]

They are pretty neat and so simple on top of that. Thanks for watching.

[@steve-si3oz]

Thank you!!

[@TheOffsetVolt]

You're welcome!

[@davidluther3408]

I AGREE WITH YOU ON THE COMMERCIALS THEY INTERRUPT MY THINKING WHEN I AM TRYING TO LISSEN TO THE VIDEOS.WHERE DID YOU GET THAT STAND FOR YOUR PS AND,O SCOPE?I AM LOOKING FOR SOMETHING LIKE THAT.

[@TheOffsetVolt]

I made it from some spare items around my shop. Best way I know to get something that does just the job you want.

[@davidluther3408]

@@TheOffsetVolt THANKS!

[@michaellagana936]

Question can you use that same antenna to transmit a signal?

[@scottmorgan5370]

Could you please comment on what if any the earth's magnetic field would have on something like you have here.

[@qinaan]

Nice. Don't you think metallic gang capacitor right in the middle of the loop may cause distortion and received energy loss.

[@kensmith5694]

The fact that the capacitor is a good conductor and small compared to the loop means it will have little effect. The RF lines of force will avoid it.

[@suhailasaba1051]

Thanks for the video. Why should the length of wire be 88 ft ?

[@TheOffsetVolt]

The wire's length around the frame provided the correct inductance value. This makes it possible to get any resonant frequency in the AM band through the use of the variable capacitor.

[@suhailasaba1051]

Is it related to the value of the wave length ?

[@cameronstolhand7149]

Would wire as thin as 43 AWG work just as well as a thicker gauge wire?

[@TheOffsetVolt]

It can. The wire acts as the inductor so you will have to space those thin wires much closer together.

[@kisuke6517]

does this work without the variable capacitor

[@mmallick3224]

No, it won't work. If you aren't available with a variable capacitor, you can create your own sliding capacitor using two tubes, the latter smaller than the previous one in diameter. Wrap the larger one and smaller with aluminium foil seperately and slide larger tube over the smaller one or vice versa. Add two seperate wire over the foiled area of the tubes. As per the diameter, you'll get capacitance from 1~90 pf, which is sufficient for the MW and SW bandwidth.

[@rochtourigny8140]

Could this work with digital TV antenna?

[@TheOffsetVolt]

Hello and thanks for watching. No, this wouldn't really work for that signal type. You could build something but ....? I've played around with some digital antennas and found Channel Master CM4228HD to be good.

[@rochtourigny8140]

@@TheOffsetVolt Thank you!

[@whatislove2735]

Please let us know the rules for making this antenna by writing in the comments

[@TheOffsetVolt]

First select the frequency range you hope to cover. Let' say you want FM from 88MHz to 108MHz. You have a variable capacitor with a 10pF to 20pf (I just made one up). Plug the highest capacitance and lowest frequency in the band into the equation L=1/{(2piF)^2*C}. Using 20pF and 88MHz you get 163.54nH. This gives you the inductance you need. Build the inductor on a suitable frame. Roll wire onto it and measure the inductance as you do. Stop when you get around 163nH. To find the upper frequency, plug the lower value of your variable capacitor into Fr=1/(2pi* (sqrt of LC)). In this case the answer would be 124.45MHz. Hope that helps.

[@railgap]

preselector or tuned antenna but "amplifier"?!? Why would you use that word when you know it's wrong?

[@stevechrisman3185]

hence the quotation marks