You could also put a small steel plate in line with the coil to monitor current - the mag field will pluck it like a speaker. Tune for maximum sound rather than maximum smoke! (It would be worth put
Hi Rik, We meet something like that at work, where there are THz researchers as well as those of us interested in (V)LF. They look down their noses at it if there aren't twelve zeroes in the frequenc
Hi Mal, Thanks for your comments. However, we need to bear in mind that running two wires out to tent pegs in the ground does more than give you a double Earth connection. They can act as effective a
Hi Mal, Good point - you don't really worry about antenna efficiency at LF for Rx, but of course you do need to for Tx. I agree with what you're saying. 73, Chris G4OKW -- Dr Chris Trayner School of
Hmmm ... not so sure. He described it as free climbing. Comparing it with free climbing in the UK (and the States, before anyone suggests I'm belittling their climbers), - Free climbing is without ro
Dear LF group, I have an old Hewlett Packard spectrum analyser which I want to get rid of - free to a good home. It covers up to 300 kHz. It comprises three modules in a 19" rack case 22cm high: 1. A
Hi Andy, I have a batch of very bad (high temp coef) 22nF I sometimes use for undergrad teaching. Get the students to build an oscillator with them, watch the waveform and then grip the cap between t
This is the dark side of English culture. Commercial radio and TV are arguably as bad or worse. They are paid for by advertising; the firms which advertise get their advert money from selling product
Hi John, I have a box of 5000 1N4148s at work. I might be able to spare you the odd one or two ;-) 73, Chris G4OKW -- Dr Chris Trayner School of Electronic & Electrical Engineering, The University of
Hi John and others, It's CANBUS. It's used as a communication system around vehicles and controls all sorts of things as well as bringing data back from sensors. When Robin G8DQX and I were over with
Dear All, I think the real reason for changing from cycles/second is that the units describe the dimensions of the quantity. Dimensions in physics are relatively few things: mass, length, time etc. C
Dear all, There has been a lot of talk about what people intend to do. Surely this is irrelevant? The Law presumably says that that you may or may not radiate in certain ways - your intentions are ir
Hi Stefan, Or let it go flat ;-) Actually, I think they invented it for good economic reasons. I think it's got to the point where it's cheaper to have two power wires plus two signal wires going fro
Hi Roger, Maybe. Saying that they don't normally issue NoVs could mean that NoVs aren't needed, or that they are needed but that OFCOM would rarely grant one. I suspect that their intended interpreta
Dear All, Stefan raises an interesting issue. I'm sure you are getting high efficiencies. But measuring it at these numbers close to 100% actually makes quite interesting demands on the accuracy of t
Hi Rik and others, Absolutely! The soil charges up. It's quite fun to do. Take your multimeter into the garden, put it on the Ohms range and put the meter prods into the soil some distance apart. The
Gary, It's easy really. The centre of the civilised world is called Yorkshire. To the north is Northumberland - that's there to keep the Scots out now that Hadrian's Wall is in disrepair. To the east
Hi Jurgen, For cave radio, where we use earth connections, we typically get a few hundred ohms. We are normally in shallow soil over rock, though, so maybe you could do better. The surface area is ce
I can remember, in the 1960s I think, Radio Constructor having an entire back page advert for red spots at 15/-. I also got given an OC72 for a birthday present - it came in a little cardboard box,
Hi Mal, I think you may have misunderstood John's question. Having met both of you, I would guess that John first picked up a soldering iron not long after you learnt to read. He certainly knows how
