input then Ah. This is one of the great mysteries of loading coils that has always baffled me. Does anyone have a good explanation? Mike, G3XDV (IO91VT) Are we in a Monty Python farce here ? Are you
The LF Forum scheduled for Sunday 20th May will be held at the headquarters of the Flight Refuelling Amateur Radio Society at Merley near Wimborne Dorset. Start time is scheduled for 1100. Directions
Many years ago I had to give a presentation on a student project and used the term 'cheap' to explain my choice of components. The instructor immediately pulled me up and insisted the correct express
re Jim's comments : I have been thinking along similar lines for somewhat different reasons. I don't claim to have expertise in this field, but suppose the data rate of Wolf was reduced by a factor o
A recent discussion with G3PLX made something click in my mind about the widespread adoption of Wolf for LF communications, and is it really the right way to go ? A heavily coded relatively wideband
John et al - Consulted the reference you gave (page 14-4 in the 6th edition) and can see where the figure comes from. The value of 4.2% quoted is, as you said, the RMS value of the ripple / mean outp
Think I'm going to spend some time looking at rectified 3 phase waveforms - can't just accept a something until I know exactly why and can derive it from first principles. : The engineering mentality
That's set me thinking evil thoughts ....... 600V Mosfets in bridge. 3 phase rectifier giving 13% ripple even without any decoupling caps, at a ripple freq of 300Hz. 10kW perhaps ! Andy G4JNT voltage
But much better still a bleed choke, making sure the inductance is high enough not to affect the matching. A good choke would be made from a ferrite core and as it is not carrying any power a smaller
Wouldn't you be better off feeding a bleed resistor as well, to stop the static building up in the first place ? Or better still, a choke to make sure there is a proper DC path. Andy G4JNT I have now
Another example of a reply without the original posting being returned, what is going on ? Anyway ... I'll send the spreadsheet direct. Turns were spaced about 50mm apart - defined by the standard pi
I initially used one on 73kHz. Two turns of 10mm diameter water pipe, overall loop dia 3m. Efficiency was about -50dB compared with -40dB for a modest 7m high T antenna so the loop went in the bin. H
I have been given a small compass module that, apart from magnetic heading, gives a serial digital high resolution output of X and Y components of the Earths magnetic field. Added a simple PIC + S/W
Instead of trying to control nanosecond long crossover problems and skew in driver chip propagation times, why not employ the Decca Tx approach of a small value (damped) inductor between the top and
One option would be to use the TC4428 driver chip. This has one inverting and one non inverting driver. Drive both inputs in parallel and connect the FET driver transformer primary, now with twice as
What sort of Tx is it ? Andy 'JNT Dear LF Group, I got my new 73kHz TX running with suprisingly few problems (so far...), so will try running a beacon signal tonight on 71.924kHz, 30s dot QRSS, start
Could this path be enhanced by the Earth / Ionosphere waveguide propagation mode, prevalent at lower frequencies. I know it is rather too high frequency to be normally considered for this mode, but w
About this time last year I seem to remember sending some narrow bandwidth SMT Hell sigs at powers of a Watt or so. With the QRP discussion going on recently, is anyone interested if I set up this be
