I used an RA1792 for all my narrow band LF work, and it was performed admirably. The PLL synthesizers appear to have good phase noise performance, and they can be used down to 8kHz - at which point y
I've made both quad helix and crossed dipole GPS antenna in the past - the details are on the web somewhere if you search - but its hardly worth it now - they are so cheap and available surplus. Andy
My 700W design used 500V IRF462 devices in half bridge running from a 340V rail - not a massive design margin there. I used transformer drive direct to the devices, with the transformer primary drive
Thanks for your responses to this. I reduced the burden resistor to 440 ohms (for 0.1V/A) and got adequate linearity (with only 1V across the 240V secondary ! ) and have now managed to capture the vo
Rik - Oops. typing mistake there - the 0.3V came from 5 turns put on to test, so the 4000 turn primary was correct. Alan - I don't see how a rule of thumb can give a fixed number of tuurns per volt.
Can anyone help with this knotty annoying problem... I wanted to make a 50Hz current transformer (CT) to measure the input current waveform to a SMPSU. I took a small cheap transformer from a wall mo
John - Yes please, if you could send the screen dumps and info to my work email address (its faster) -- [email protected] I'm surprised that you say the improvement with Africam was not that signi
I will be giving a talk at the HF Convention on the use of GPS to enhance amateur communications methods. Seem to recall talk about a few datamode software authors who were contemplating adding some
The word s_cret. perhaps ? Are there specific words that trigger the anti-spam policy of this reflector ? I tried two times to answer Alan's message, but apparently both messages have been silently d
If you drive FETs directly from a driver IC, when the FET blows up the gate shorts to the high voltage, which feeds back and blows all your driver circuitry too. I learned that the hard way when desi
As an experiment to gain some experience with using the soundcard (long after everyone else has already done it!) and to see how good Visual Basic 6 is at real time audio DSP, I ve written a couple o
This was the output of a Garmin GPS module as the leap second happened... There were 61 seconds in the last minute of 2005. $GPRMC,235955,A,5054.5848,N,00117.4051,W,000.0,000.0,311205,003.5,W*7B $GPR
I've put a selection of software and a few write-ups of past projects on www.scrbg.org/g4jnt. The archive will be updated gradually as time/inclination/list-of-things-done changes. Andy G4JNT
By permission of QEX, I've posted the full version of the 700 Watt 137kHz switch mode Tx that originally appeared in the Nov/Dec 2002 issues on www.scrbg.org/g4jnt/ This generated RFdirect from recti
When I used to listen 30 years ago on AM in a wide(ish) bandwidth at ~1900kHz, it sounded like a bell jangling - was this the same signal as your 'bandsaws' ? The signal was often referred to as the
I seem to remember it sounding even more melodious that when listening on AM - as I did then to the local amateurs net in the Birmingahm area. I presumably received an amorphous mass of several of th
A professional programmer who spent somef time working on waterfall palettes for signal analysis once suggested that, it order to see signals separated from the background by only a small amount, a w
Can someone help with what should really be obvious. I have a train of constant width pulses at a fixed repetition rate. In the frequency domain these appear as a spectral comb with spacing at the re
Yes - that's the obvious bit I was missing - go back to first principles and do the actual Fourier transform on the waveform. There ought to be a short cut, though, knowing the integral is finite and
