I needed an accurate attenuator for a work experiment I wanted to do at home (recovering from a dental surgery — I’m fine 🙂) and a friend had this beauty taking up space 🤷🏼‍♂️🙂 (I have good friends).

Clearly hand built (sorry for the shaky video), made to sit in a test rack, remote controlled by the vintage Z80x CPU board. It’s quite flat in its frequency response (I had troubles with the VNA calibration, so you’re seeing cable and connector loss) and I made a couple spot checks at 3 and 6GHz, 1.5 and 2.5dB loss respectively.

Attenuation accuracy is within +/- 1dB.

This is quality vintage stuff, dated about 2003 from the onboard chips. Don’t you just love the Teledyne RF relays? 🥰

Oh, and it works way below the stated 2GHz, I tested it down to 10MHz and it was just fine 👍🏼

#rfengineer #rfengineering #frequencyfriday #hamr #hamradio #testandmeasurement

The 74LS123 is ‘retriggerable’, this means that if it gets retriggered while already active, it starts all over, keeping the output state ‘high’ (or ‘low’ if inverted) for the designed output pulse duration until the next trigger signal arrives.

This basically means that if the trigger signal occurs at shorter intervals than the output pulse duration, the output will stay active permanently.

Why would you ever want this?
One application could be to strip off some modulation of a digital signal, as an example the flickery LED candles.. They’re pulse width modulated: I can remove this with the 74LS123 after which, the random flicker sequence will be ready to capture and analyze 🙂

Stay tuned for my next post 👌🏻🤓

#frequencyfriday #electronicsengineering #testandmeasurement #engineer #siglent #ttl #digitaldesign #ttlelectronicas #electronicsdesign

A small walkthrough of my hydrogen line radio telescope, seen through an app which does a really cool AR overlay of the Milkyway.

What happens when I point the antenna to a vertical position, far away from the galaxy?
To things: 1) the 1420MHz signal disappears and 2) The noise floor drops several dB. Effectively this means at I’m picking up ground noise at this low view angle 👌🏻

#radiotelescope #astronomy #radioastronomy #rfengineer #rfengineering #hamradio #hamr #siglent #frequencyfriday

10 years back, I started experimenting, building my own radio telescope. My results, trying to observe the Galaxy hydrogen line at 1420MHz, were positive but in no way impressive.

Years have passed, I have better test equipment today, I have my own lab and I have a better antenna 🤓 📡

So I decided to give it a go last night - and it worked!

Not ideal a summer evening like this, the sky temperature is too high, and my observing angle too low, but at least I proved it possible, it’s a nice starting point 🙂🙂

My setup is a vintage 17dBi standard gain horn and a 38dB LNA, cooled about 20degrees below ambient. I feed this to my spectrum analyzer.

Next step will be to build a larger antenna and try again with when everything cools down in the fall 🙂

I really looked forward to share this - I hope you appreciate it 👌🏻☺️

#radiotelescope #astronomy #radioastronomy #rfengineer #rfengineering #hamradio #hamr #siglent #frequencyfriday

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

It's a #FrequencyFriday. Here's where to listen for the #ISS on #HamRadio as it passes overhead.

Check status of radios at https://www.ariss.org/current-status-of-iss-stations.html