Tnx for the report. I was playing about with the settings looking for suitable sets of frequency span / pixel intervals for Argo, and decided to leave it going at high power as conditions seemed quie
Correct :-( But someone has now forwarded the semaphore alphabet so when a few idle few minutes come along .......... More seriously, we can go on inventing new signalling methods and alphabets ad-in
Sort of suggests a Multifrequency Version similar to SMT Hell. There's a thought. :-) Easy to do with the DDS driver. What is the Semaphore alphabet ? Andy G4JNT One other mode that never failed (see
If 350mW can be heard then there is a slight hope for me yet :-) At 1920z, just started transmitting transmitting a DFCW signal with 0.05Hz shift and 90s dot period (for compatibility with Argo on it
The GPS25 module - one of those recommended by TAPR for the "GPS Disciplined Frequency Standard" - is specified as having a 1 PPS output accurate to within 1 microsecond of UTC. Additionally, it is s
So 'JNT was visible and understandable then :-) I was finishing off the DFCW software for the DDS module after seeing Laurie's signal in real time, and modding it so gap length could be programmed se
--Original Message-- From: James Moritz Subject: LF: Beacon signals long dots and dashes, and took about 1hour 20mins to send the complete call. Does anybody know of a keyer program available for .lo
There has been so much discussion on Wolf and BPSK spectra on this reflector recently that it seems a prime topic for the forthcoming LF Forum on 20 May at Flight Refuelling HQ nr Wimborne. Has anyon
The 16kHz transmission is MSK (Minimum Shift keying). An efficient, constant amplitude, data modulation format. There was quite a bit of discussion about the mode on this reflector a few months ago,
Due to a major c__k up here, I have not received any external EMail on the works account since yesterday morning, including any messages from this reflector. So Mike 'XDV, if you have posted a summar
You've made me think about it a lot more now. The AC/DC resistance argument is certainly valid. It does indeed mean that any capacitive field will be captured with less loss than letting it end up in
But these harmonic currents will upset your readings somewhat - where on a scope trace is the RMS value of a) the total waveform and b) the fundamental ? The harmonic currents will obviously be out o
I measured the thinkness of some (Sainsbury's own brand) foil at 0.03mm. This equates to 0.13 skin depths. It is even worse. I read the micrometer wrong, a very ancient one calibrated in those US uni
Steve and group Aluminium kitchen foil is much thinner than the skin depth at these frequencies, so you are getting nowhere near the full screening effect. Skin depth is given by 503.SQRT(Rho / Freq)
I would have thought the stray capacitance associated with the ammeter when measuring current at the top of the coil would cause more than enough detuning to reduce the current by this much. But ther
The measured voltage was 8 volts peak-to-peak, corresponding to a power of about 60 mW. 8V p-p in 50 ohms is 0.16W, not 60mW So you have 34dB coupling - you were right to expect more than 40dB ! Andy
Why ? I did look at this, and came to the conculsion : Peak of one cycle falling to the 60 degree point, SIN(60) = 0.866. So ripple = 1 - 0.866 = .134 hence 13.4% I did hear once that some high power
Wait a minute ! I = SQR(W / R) so current in the loop = 51.2A and voltage at the feed is this current in the 60 ohms reactance, ie. 3077V Andy G4JNT --Original Message-- From: Dick Rollema <d.w.rolle
Alan - We need to be realistic about the types of inductor feasible for transmitters at this frequency. With an antenna capacitance of 270pF and inductor of 1.2H or so at 9kHz, the number of turns ne
