Hi Stefan, Have you done any more tests with this? I am curious to see the results. Would this idea work on VLF as well? I have come across some power toroid transformers that have a reasonablywide u
Hi Stefan, it's always worth giving it a try! There are people that use toroid power transformers as valve/tube output transformers. So don't disregard them for audio use! I agree that the efficiency
Hello group, I have received an email from a friend in Japan informing me that Japanese amateurs gain access to 630 m from 05/Jan/2015. There are some restrictions on power and vicinity to other hous
Hi Hideho san, Thank you for the update. I am glad to hear that even though you have all these tough restrictions, Japanese amateurs are planning portable operations in the new band! I have not heard
Hi Hideho san, In Australia, for frequencies below 30 MHz we need to reduce our harmonics by the lesser of: 1) 43 db + 10*log(PEP) 2) 50 dB where PEP is peak power to the antenna. When I was allocate
Hi Hideo san, On VHF and higher frequencies, the harmonics need to be -70 dBc. Conceivably, a 50 MHz transmitter harmonic could land on an FM BC station's frequency so this is the same problem as whe
Buongiorno Mauro, a few months ago, I build a single turn loop, 0.7 m by 0.7 m, using very thick electrical copper wire. I resonated it on 160 m using a couple of beefy silver mica capacitors in para
Hi Mike, we never had a 185 kHz band in OZ. From memory, many years ago, some individuals got scientific licences and did some experiments there, but it was never an open-to-everyone band. We do have
Hi Stefan, Maybe the ground-wave propagation curves in this ITU document shed some light? In this document there are curves for sea water (various salinity levels), fresh water and land (various cond
Hi Markus, very nice experiment! I did something similar some time ago: http://people.physics.anu.edu.au/~dxt103/472/small_loop/ I would like now to make a larger loop using a 20m thick coaxial cable
Hi Stefan, new callsign and new QTH indeed. I am now outside the city, the nearest house is about 300m away from mine. I also have some space, about 20 hectares, so expect more traffic on LF/MF :-) O
Hi Stefan, all your good suggestions noted! Hmm, that's about 2 km of wire, my place is not big enough, but the people around me seem to be quite friendly, so I guess it's possible. What sort of wire
Hi Stefan, By chance, and after I picker the COW callsign, I discovered that the QTH locator is the appropriate QF44ox :-) There is a lot to consider. I am still unpacking boxes here, so I have been
Hi Alex, very interesting, thanks for your information. The challenges in my case would be keeping the kangaroos, wallabies and wombats away from the wires, but at least the temperatures are a bit mo
If this is of any use to anyone, I have made a simple online calculator: http://people.physics.anu.edu.au/~dxt103/calculators/toroid.php 73, Dimitris VK2COW
Hi Joe, thanks for sharing your experiment details. I have been doing similar tests on VLF, using about 120 m of wire, about 10 m of the ground. I have used initially much less power, so signals disa
Hi LF group, I have managed to acquire a few very large ferrite rods (36 cm x 10 cm x 2 cm). The material is unknown but I managed to form a square 'toroid' with four of them (they are heavy so gravi
Minor correction, the calculated relative permeability should be about 500, I made a mistake in the initial calculation. I just discover why they call it initial permeability (bad joke) :-) 73, Dimit
Hi Clemens, the mistake I made the first time was that I incorrectly set the ID/OD difference of the equivalent ring to be 2 cm instead of 4... 73, Dimitris VK2COW
