Adding parallel circuit allows for the Lambda Diode to oscillate at a frequency determined by the LC resonance frequency. The result is an absolutely beautiful sine wave 🤩

Note how the oscillation starts, once the supply voltage crosses where the current starts to decrease, ending up at the ‘negative resistance’ portion of its characteristic.

This is likely the easiest and most clean oscillator I ever built 😃 I wonder if you can use a crystal or crystal f it would get damaged from the drive level 🤔
Maybe one of those vintage ones..

@va3db

#signalsaturday #electronics #rfengineer #testandmeasurement #hamr #hamradio #electronicsengineering #siglent

The Icom IC-7000 I recently purchased is quite old and they’re known for having a bit of high frequency ‘hiss’ in the audio output.

I doesn’t matter while using the built-in speaker, however it gets annoying when using high quality headphones. There is a fix, but it’s complicated and involves extracting a major PCB from the radio.

I had some random two-way speaker filter in a drawer so decided to give it a go at reworking it, to become a 700Hz lowpass filter (I’m primarily a CW operator).

It turned out really nice, even peaks a bit before rolling off.

And the ‘hiss’ from the radio? Gone! 👍🏼😃

#hamradio #hamr #icom #icom7000 #siglent #electronicsengineering #signalsaturday

If there’s an application where a good old analogue oscilloscope will deliver right away, it’ll have to be the classical #hamradio two-tone modulation test 😃

Using the #Cutegen™️ and a resistive mixer, I’m modulating a #yaesuft817 with two tones: 700 and 1900Hz, observing the resulting RF signal on a spectrum analyzer and the oscilloscope.

A simple and traditional way to detect unlinearities and observe transmitter performance. And it’s an absolutely beautiful picture on the oscilloscope screen ☺️❤️

All time RF engineering and #hamr classic 🙂

#signalsaturday #testandmeasurement #rfengineering #rfengineer #electronics #electronicsengineering

It’s #signalsaturday and I’m continuing the #CuteGen™️ test series by looking a bit at the harmonics 🙂 How clean is it?

Starting at 1kHz I’m using my #Siglent #oscilloscopes powerful FFT functionality and with harmonics >60dB down, this little thing really is a decent audio function generator.

I then moved to the spectrum analyzer and did some tests at (much) higher frequencies. Only included 10 and 30MHz here, but pattern is clear: harmonics are generally nicely attenuated, more than 60dB, although at the high end, it’s not quite that much, more like 50dB and a sub-carrier spur appeared as well. Makes me wonder how well the 60MHz version performs 🤔

#testandmeasurement #rfengineering #rfengineer #electronics #electronicsengineering #uni-t #hamradio #hamr

Inspired by #keysightlabs and #danielbogdanoff, latest YouTube video, where he uses a super nice #keysightoscilloscope to demonstrate reactive (negative) power, I decided to make my own setup and replicate his experiment.

I don’t have an advanced scope as the one he used, but I can create a voltage vs current phase difference by changing the frequency of a signal I pass through an RC circuit.

Measuring the current with a differential probe, lets me multiply current and voltage and display a power curve on the oscilloscope (sorry for the weird colors, my camera messed up).

As you can see, with a phase difference between voltage and current, I get negative power: the top curve begins to move below zero. At 90 degrees difference, the power would average zero which is why inductors and capacitors never really heat up (besides the resistive loss ofc) 🙂

#electronics #signalsaturday #siglent #micsig #engineer #electronicsengineering #testandmeasurement #hamr #hamradio

It’s #signalsaturday and here’s a quiz: what happens if you add two sine waves, not through a mixer, but simply by a couple of resistors?

They literally get added on top of each other 👌🏻👍🏼😃

This may seem simple and obvious to many of us, but fully understanding this rudimentary experiment is the first step towards a new path in life, where time- and frequency domain always goes together 👌🏻🙂

#electronics #electronicsengineering #hamradio #hamr #testandmeasurement #stem #engineer #rfengineering

It’s #signalsaturday and here’s a mystery SW signal I picked up at my friends place 😃

5-15s bursts, centered at about 1.5MHz, total bandwidth 2MHz. Starts with carriers 4kHz apart, then spreads out to a noise field, which then goes back to single carriers.

Mostly present weekdays, signal is ‘local’ ie not observed on SDRs further away. No apparent timing of the bursts, occurrence seems ‘random’.

Either it’s 1) alien 👽 (joke) or 2) Some communications channel or 3) some kind of VFD 🤷🏼‍♂️
#hamradio #rfengineering #rfengineer #thetruthisoutthere

Inspired by a Twitter dialogue, let’s launch some daily #electronics tags to be used freely 👍🏼🤓

Today is #waveformwednesday and here’s how my mains grid looks - not quite a sine but that’s to be expected.

Don’t ever, EVER, connect your scope input directly to mains - use a high voltage differential probe or a transformer, as shown here.

I’m using the #quicktest switch, it’s a really handy way to control power to a circuit. It’s of British origin and comes with a standard 13A BS1362 fuse. I found that a bit high for my purposes, so I replaced it with a 5A, significantly limiting the available energy in case of a fault situation. Safety first always applies at the bench 👍🏼⚡️☝🏻

So go ahead, use these tags freely, be inspired and show us your experiments 👌🏻🙂

#electronics #rohdeschwarz #micsig #electronicsengineering #engineer #hamradio #measurementmonday #testgeartuesday #waveformwednesday #teardownthursday #frequencyfriday #signalsaturday #sensorsunday