You might find this interesting. Years ago I designed some fixed frequency radios for the US Navy. When I started, I took some transistor radios and tested them at colder and colder temperatures Until the radios stoped working. I then investigated to out why. The problem turned out to be the ferrite cord on
I have a question for you. Which Would love a higher Q. And more sensitive reception. A naturally tuned coil to a certain frequency, or a coil tuned with a capacitor? I am looking at receiving a frequency of 720 kHz
For highest "Q" I would always go with an air core loop. Plus it is physically larger. I would tune it with the minimum amount of capacitance.. say 100 pf or so. When using an inductor in parallel a good quality cap like silver mica or air variable, the "Q" of the circuit will almost always be dominated by the coil. go for a coil at least 18" on a side. W1VLF
It's a very good idea~ If the AM broadcast frequency is in the range of 535~1605KHZ, the center frequency is 926KHZ~ If you tune based on this frequency, you won't have to go through the trouble of turning the varicon every time~ And if the receiver's external antenna input impedance is 50 ohm or 75 ohm, it doesn't matter, but if there is no separate external antenna terminal, the impedance is very high (about several K ohms), so you will need a transformer to lower this impedance. Personally, I made an amateur band antenna for 3.5MHz and 7MHz with a 1m long ferrite bar antenna, and it was possible to receive it indoors despite its short length~ I hope you have a fun hobby~^^
I love listening to the AM radio band I belong to the IRCA AM radio club International Radio Club Of America are you going to sell these ferrite loop antennas
I just made a pizza box loop that works very well. It`s 16 turns of 24 AWG magnet wire on a 16 inch pizza box with a 450 pf tuning capacitor. There`s a demo of a station being tuned in over 140 miles away on my channel.
to some extent yes... In experiments, I have doubled the length of a single 7' ferrite rod to 17 inches and there was some increase in signal strength, beyond that is is doubtful there is much to be gained in MW band W1VLF
I enjoy your experiments with simple portable ferrite & frame loop antennas. A couple of comments from me......You can inductively couple a ferrite loop & a frame loop antenna together. This would require a separate variable capacitor for both. Using litz wire is expensive & difficult to solder. I've had reasonable success using small diameter enamel and/or plastic insulated solid & stranded wire. Being a ham/swl, i like the capability of using either antenna on 160/80 meters receive. Walmart & some dollar stores sell plastic water guns. A small diameter plastic tube is inside a larger plastic tube. The small diameter plastic tube can be pushed & withdrawn. The combination of both tubes would make an excellent container/holder for an experimental ferrite loop antenna. Basically this would be a giant variable loop-stick or antenna tuner. Thanks again for your simple receive antenna contributions. I look forward to more of your experiments.
Hello Yes... If this were at night.. It would be old reliable WTOP now WFED, during the day it is WFIF in Milford CT... Thanks, you inspired me to look that station up. W1VLF
How ican matching ferrite antenna with lower imput impedance mean how to calculate number of secondary turns to matching with this lower imput thank you
I did not calculate the number of turns. I designed mine through experimentation. I usually wind more turns than I need and then it is easy to take one turn off at a time to peak the signal transfer into your receiver W1VLF
I wish you were my neighbor. You probably would not like that, as I would be asking you questions all the time and picking your brain constantly - what a wealth of information you would be for me! I'd pester you constantly!! Thanks for your videos!
Hi I'm trying to find some RFI using my AM radio and it's built-in ferrite antenna. I assume the ferrite rod is on the top of the radio. How do I know WHERE a signal is coming from. With the front or back of the radio pointing at the noise or the left or right side of the radio where the signal might null out???
Is the math correct if you use a ferrite ring (like 12 cm across) and wind the wire coil on a small section of that ring like you did on the stick, Does the ring need a gap (1 cm) to make it function the same way?
Links to the ferrite rods? Schematic and construction details? Great video. Going to try and receive the Xmas eve transmission of the motor generator generator in Sweden on 15.7 kHz. Any antenna suggestions?
I believe that the Christmas Eve transmission from SAQ in Sweden has been cancelled due to Covid 19. I have received it on previous occasions using a YouLoop antenna with my Airspy HF+ and also with a MiniWhip antenna and an upconverter + RTL-SDR v3. I am in Southern England, so perhaps its a lot easier here.
Is this what the Ccrane double ferrite antenna is could you make a larger one and put it up on a metal roof and turn it remotely to null out noise for a base reciever for low band and mw am . Possible other project. Great info I'm learning more on each video. Keep it up. And thanks AA4CP Chuck Patterson
Very informative. Thanks. Is it posible to screen a rod antenna like this to only receive from one side, to possibley determine the direction to the transmitter ?
It definitely has an effect on being able to have symmetrical nulls.. They still occur, but as deep and not in the direction you might think the station is
Great informative video and I now have ferrite rods, Litz wire and a variable cap on order. Hoping you will post the number of primary turns to save us from fumbling and wasting expensive Litz wire.
Hi Mike... at the end of the video I show the amount of turns in this particular design. How ever I will do some with regular magnet wire.. Yes... Litz is expensive. W1VLF
