Nostr notes by Søren Kjærsgaard

Have you ever biased a LED at 30mA? They really light up! ...

2026-09-27T19:54:43Z

Have you ever biased a LED at 30mA? They really light up! 🤷🏼‍♂️😂

Not all LEDs will survive this continuously but the UV5TZ series can, and they’ll happily deliver above 20mW UV-A at around 400nm at that bias.

Current control is important and my #keithley 2400 source measure unit is the perfect companion for the job.

I need to build a constant current generator so I can make a powerful UV flashlight ☺️

#electronicsengineering #testandmeasurement

Could you put the video somewhere I can download it? (Dropbox ...

2026-09-27T16:28:23Z

In reply to nevent1q…y60s
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Could you put the video somewhere I can download it? (Dropbox link, maybe). I’d love to save it, since it was my final summit in OZ, completing the entire region (I also happen to be the OZ regional manager ☺️)

I’d absolutely love to 🥰

2026-09-26T19:24:39Z

In reply to nevent1q…qe3j
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I’d absolutely love to 🥰

#hamradio #SOTA trip, objective was to activate the remaining ...

2026-09-26T17:54:32Z

#hamradio #SOTA trip, objective was to activate the remaining three summits in Denmark I had yet to visit.

Fantastic trip, lovely crew and company, nice foods and drinks 🍷 🍺👨‍🔬☺️

Mission complete! As the Danish SOTA administrator, I have now activated them all ☺️

Thanks for all the QSOs dear friends ☺️

Best 73

my final summit in OZ, now I have them all 😃

2026-09-26T14:11:09Z

In reply to nevent1q…4ckr
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my final summit in OZ, now I have them all 😃

TNX for QSO ❤️🙂🙂

2026-09-26T14:03:32Z

In reply to nevent1q…y60s
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TNX for QSO ❤️🙂🙂

Thanks! 😃 73

2026-09-20T14:14:02Z

In reply to nevent1q…x9ff
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Thanks! 😃 73

#hamradio This weekend is the SAC (Scandinavian Activity Contest) ...

2026-09-19T16:51:03Z

#hamradio This weekend is the SAC (Scandinavian Activity Contest) CW section: everyone outside Scandinavia wants to contact ME (and so many other nordics). It’s THE single yearly event for me as a #CWOPS (CW/Morse operator), the bands are buzzing with life, it’s a joy 🤩 Oh, and my assistant is evaluating the performance of the PSU fan (which runs frequently ☺️)

73 de OM OZ1LQO 👌🏼

New one for the collection 🤩 eBay find, really nice build ...

2026-09-16T05:24:15Z

New one for the collection 🤩
eBay find, really nice build quality and easy to assemble. About €130 including shipping 👌🏼Will be fun to try it out ☺️

#hamradio #rfengineering #3cm #microwaves

Wow, look what came my way! 🤩 A fully functional HP-25C, ...

2026-09-08T20:07:38Z

Wow, look what came my way! 🤩
A fully functional HP-25C, production date week 5 1977 (1960+17) in S(ingapore). A couple of alkalines easily replaced the built in (dead) rechargeables, which luckily hadn’t leaked.
Need to find a manual for this gem 🥰
#RPN #vintagecalculator #hpcalc

See my previous post 😎

2026-08-31T16:14:59Z

In reply to nevent1q…pfmg
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See my previous post 😎

My entire setup is based on a BAT15 diode, soldered across the ...

2026-08-28T14:09:07Z

In reply to nevent1q…e3fp
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My entire setup is based on a BAT15 diode, soldered across the antenna terminals. Feeding it 4965.5MHz gets doubled to 9931MHz. Any 10368 signal entering the antenna, will be mixed with that, producing the 437MHz.
Rudimentary, low sensitivity, but it works.
I don’t expect DX with this 😂 But it’s a cheap setup to get on-air at 10GHz. Pretty much the cheapest possible unless you buy a transverter or find some old gunnplexer (they’re hard to come by and has horrible frequency stability)

Last test - does it receive as well? I don’t have a 10GHz ...

2026-08-27T17:22:07Z

Last test - does it receive as well?
I don’t have a 10GHz generator, but I figured that third harmonic of my cheap ADF4351 would be powerful enough for me to pick it up.

Set the generator to 3456MHz (beautiful 🤩) and third harmonic will be at 10368 and it should display as a 437MHz carrier… It does 🥳

I need to find someone to talk to… 🤷🏼‍♂️☺️

It’s been a fun process though, probably the simplest and cheapest 10GHz transceiver you can build ☺️

Next post on this project will be a real QSO 😎

#hamradio #3cm #rfengineer #rfengineering

First 10 GHz transmission #hamradio ...

2026-08-26T19:57:26Z

First 10 GHz transmission #hamradio

I did it! First 10GHz transmission across the house, using a LNB ...

2026-08-26T19:56:29Z

I did it! First 10GHz transmission across the house, using a LNB and my R-8600 as a receiver. Signal generator is running at 4965.5 MHz, that get doubled at the mixer diode in the antenna (se earlier post) and added to the 437 MHz transceiver signal.

It works! 😃😃

Now I need someone with a similar setup to do a real QSO ☺️

#hamradio #3cm #rfengineering #rfengineer

yah, it’s kinda sad to see those bands, once ever so active, ...

2026-08-10T06:50:22Z

In reply to nevent1q…m3md
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yah, it’s kinda sad to see those bands, once ever so active, now silent, maybe forever. We’ll see. Maybe sometime in the future, there might be a revival. AM Radio crosses borders without censorship and can easily be received by a simple, battery driven, unit. The way we’ve setup our global, internet driven, society is smart and I fully benefit from it as so many others do. But it makes us vulnerable 🙂

Nice 🙂 I just ordered the ‘Bullseye LNB’. Together with my ...

2026-08-09T20:37:44Z

In reply to nevent1q…9t0d
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Nice 🙂 I just ordered the ‘Bullseye LNB’. Together with my R-8600, I’ll have a decent test receiver for my 10GHz experiments 👌🏼🙂

😂👽

2026-08-09T20:14:03Z

In reply to nevent1q…3tcy
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😂👽

Here’s DWD 🙂 ...

2026-08-09T20:06:42Z

In reply to nevent1q…rfq7
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Here’s DWD 🙂

I built the ‘Hoop Loop’ 🤩 A small active loop antenna, ...

2026-08-09T20:05:44Z

I built the ‘Hoop Loop’ 🤩

A small active loop antenna, first featured in Elektor Magazine 01/2000, then recently in ‘SPRAT’ (GQRP magazine). It’s a dead simple amplifier, proper biasing is non existent, so I had to match the transistors.
12 windings on an embroidery hoop, then assembled in a small wodden box to give it a retro look ☺️

Works quite well, receives DCF77 just fine and also the RTTY transmissions from DWD (Deutsche Wetter Dienst).

What fun project, albeit a bit after it’s time: these days there’s only a few commercial stations left on LW and MW 😟 So much empty band which could be used for so many things ☺️

#hamradio #rfengineer #swlistener #bcl

Seems there is only one (expensive) option: Kuhne. But before I ...

2026-08-09T17:55:57Z

In reply to nevent1q…yjck
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Seems there is only one (expensive) option: Kuhne. But before I make that leap, I want to do a couple simple experiments first. Range will be much lower, but at least I can say I tried on my own, before taking the big step ☺️
Along the way, I’m now the proud owner of a 33dBi dish, so if (when) I get the transverter, I’ll be well prepared 🙂

One thing is maximum output power - next step is to verify the ...

2026-08-08T12:14:40Z

One thing is maximum output power - next step is to verify the transmitter doesn’t overshoot, thereby risking damage to the mixer diode.

Using a wideband detector I was able to display the RF power ramp on my oscilloscope, and it looks just right 👌🏼👍🏼😎

#hamradio #rfengineer #rfengineering #microwaves

For my simple 10GHz (3cm) #hamradio experiment, I need an IF ...

2026-08-08T12:07:36Z

For my simple 10GHz (3cm) #hamradio experiment, I need an IF transceiver, but it can’t be too powerful because I risk damaging the BAT-15 mixer diode, which is limited to a maximum of 100mW.

I found the Kenwood TH-F7 to have the lowest output power possible, and adding a 3dB attenuator, brings it a further down. For all the RF geeks, yes I know, this will degrade my NF, but remember this is an experimental setup, how easily (and cheap) can you get on air at 10GHz.

I’m not looking for 10km here, I’m aiming towards a portable setup to activate #SOTA and #POTA at the 3cm band with a fellow ham, using similar simple equipment.
I’m likely the first in the country to do this 😎

Stay tuned 🤓

#rfengineer

At IG, there was a comment on my receive setup, and I admit ...

2026-07-30T08:04:51Z

At IG, there was a comment on my receive setup, and I admit it’s quite rudimentary, since my Spectrum Analyzer only covers to 3.2 GHz. There’s loss in the cable (although it’s high-end) and I don’t have an LNA… What to do..

I added an active mixer, based on the LTC5549. It has a frequency doubler at the LO input, so all I needed to do, was to feed it 4GHz and as a result, a 10GHz signal would be conveniently placed at 2GHz 😎

This is obviously far from ideal: there’s conversion loss (8dB), phase noise from the cheap generator, and a horrible noise figure… However! It’s good enough to prove that there’s something there 🙂

Next step in my 10GHz setup will be to add a low-power transceiver and try to get on-air ☺️

#rfengineering #hamradio #SHF #rfengineer

Decided to try a simple 10GHz setup, I mounted a BAT15 mixer ...

2026-07-29T15:59:08Z

Decided to try a simple 10GHz setup, I mounted a BAT15 mixer diode across the terminals of the green horn and fed it a 5GHz signal. It receives just fine across the table 🥳😃

My analyzer only covers to 3.2GHz so I needed to mix on the receiver side as well -> tons of signal loss and phase noise from my cheap generators, but it certainly works.

All I need now is to add a transmitter and some filtering, and I’m basically on-air on 10.368GHz 😃

At least for a couple kilometers, but it’s enough for a first, cheap, experiment. I need to have someone duplicate the setup, so we can have a real QSO 😎

#hamradio #microwave #rfengineer #rfengineering

Look what came my way! 🤩 33dBi at 10GHz. Has a proprietary ...

2026-07-15T08:52:49Z

Look what came my way! 🤩
33dBi at 10GHz. Has a proprietary circular WG, so I need to machine some kind of interface ☺️
#hamradio #rfengineer #rfengineering

Yup. When you’re a science and electronics nerd (like me), ...

2026-07-10T15:37:57Z

In reply to nevent1q…wtwf
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Yup. When you’re a science and electronics nerd (like me), there are things you just can’t throw out 😂

Found an Agilent 5519A laser, another one of those “you or the ...

2026-07-09T19:30:21Z

Found an Agilent 5519A laser, another one of those “you or the dumpster” moments 🤷🏼‍♂️😂
It works but it’s not overly powerful (it’s not supposed to be). My cat went nuts though, so all is good 🐱😂

First time I ever see laser light from a real tube 🥰

Now what? I don’t know the pinout of the connector, I’ll have to see if I can find a schematic somewhere..
And do a teardown OFC 🙂

#laser #testandmeasurement #electronicsengineering #physics

Fellow #rfengineers out there - anyone has the data on this ...

2026-06-18T11:31:02Z

Fellow #rfengineers out there - anyone has the data on this specific (option 13) variant? Can’t seem to find anything, maybe it was specially made for a customer. I guess I can work it out, but it would be nice to have the actual datasheet ☺️ #hamradio

An active power rail probe may be useful to offset the DC of a ...

2026-06-14T19:16:52Z

An active power rail probe may be useful to offset the DC of a power rail, enabling a much more detailed view of noise or other kinds of artifact’s 👌🏼🙂
#rfengineer #electronicsengineering #testandmeasurement

it doesn’t remember across bands, but it has latching relays so ...

2026-06-04T05:26:22Z

In reply to nevent1q…pde7
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it doesn’t remember across bands, but it has latching relays so once you’ve tuned the band you want to work, it’s power drain is minimal. Works from 0.5W 🙂

#hamradio /P trip with friends, and 🐴 (also friends ☺️). ...

2026-06-03T20:15:02Z

#hamradio /P trip with friends, and 🐴 (also friends ☺️). My LNR did amazingly well, so I had to check the power output when I got back - 1.7W 🤩
#cwops #portableops #qrp

I actually had a 8086 based PC, I replaced it with a V30 and ...

2026-05-28T06:57:35Z

In reply to nevent1q…d9sp
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I actually had a 8086 based PC, I replaced it with a V30 and added a 8087. Took me safely through university ☺️☺️

Those who know, knows ☺️☺️ #electronics #vintagecomputers ...

2026-05-28T05:15:10Z

Those who know, knows ☺️☺️

#electronics #vintagecomputers

Happy world #metrologday I’m celebrating by making noise ...

2026-05-20T06:48:22Z

Happy world #metrologday I’m celebrating by making noise measurements on a range of voltage references I’ve had powered for more than a year ☺️🥳 worldmetrologyday.org

I tested the R-532 sensitivity, found a ‘vacant’ channel. ...

2026-05-16T07:27:06Z

I tested the R-532 sensitivity, found a ‘vacant’ channel. Vacant, as in no spurs or external disturbances. It shows 236nV for 10dB S+N/N at 30% modulation depth, that’s REALLY good for a 1984 unit 😳

But it coincides well with the last couple days on-air tests, it’s as sensitive as my other receivers.

This is a keeper! 🥰🤩

#rfengineer #aviationgeek #testandmeasurement #hamradio

Look what came my way!! The legendary R-532 Airband receiver, all ...

2026-05-14T18:14:24Z

Look what came my way!! The legendary R-532 Airband receiver, all discrete, no MCU. And it works flawlessly!
Needed a cleanup and a backup battery replacement (luckily no leaks!) but at just EUR 20, this was a total nobrainer. It was only produced between 1984 and 1987, so they’re really hard to find these days.
Can’t believe my luck here 🤷🏼‍♂️🤯

#hamradio #airbands #aviationgeek #rfengineer

BTW., this is how the now disabled 50kW transmitter looked, I ...

2026-05-11T07:39:26Z

In reply to nevent1q…ddwc
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BTW., this is how the now disabled 50kW transmitter looked, I visited it some years ago.

true about the single point of fail, although if you rule out a ...

2026-05-11T07:35:02Z

In reply to nevent1q…a2nj
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true about the single point of fail, although if you rule out a direct enemy strike, where everything would change, it was actually quite stable throughout its many years of service.
I totally agree with the regional argument though, the FM towers are much better for that purpose, and it’s my impression that exactly this has been planned for by our municipalities 🙂

At least it seems we get to keep FM, now that they’re promoting ...

2026-05-10T13:04:20Z

In reply to nevent1q…s3rp
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At least it seems we get to keep FM, now that they’re promoting it for distress information 🤷🏼‍♂️☺️

a couple of years back, the Danish service at 243kHz shut down. ...

2026-05-10T10:15:52Z

In reply to nevent1q…6y27
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a couple of years back, the Danish service at 243kHz shut down. It was only 50kW, but the quality was pristine all over the country 🙂
In the meantime, we’ve all been told to go prepper style and buy small emergency radio receivers - this single transmitter would’ve covered the entire country from a single location 🤷🏼‍♂️🤦🏼‍♂️😢

and yes, I matched the transistors from ar larger batch ☺️

2026-05-10T09:19:39Z

In reply to nevent1q…2xlw
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and yes, I matched the transistors from ar larger batch ☺️

Yah, it’s a super simple setup, based on an Elektor article ...

2026-05-10T09:19:01Z

In reply to nevent1q…2xlw
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Yah, it’s a super simple setup, based on an Elektor article from early 2000’s… I don’t know how the frequency response is, but wanted to try it out, just for the vintage part and just to see how 12 vindings on a 30cm embroidery hoop would perform. It certainly works - it’s almost magical ☺️🙏🏼

Loop antennas are almost unreal… 🤷🏼‍♂️😂 It seems ...

2026-05-10T09:07:18Z

Loop antennas are almost unreal… 🤷🏼‍♂️😂 It seems almost divine that 12 turns on an embroidery hoop and a simple amplifier would let me receive BBC Radio4 on 198kHz hours after sunrise - so much more appropriate to listen to the ‘Sunday Worship’ broadcast 🙏🏼☺️

I’ve always enjoyed listening to 198kHz from my car - it makes me kinda sad they’re planning to discontinue their LW transmissions 😢 LW crosses borders, it works with a simple setup, independent of an internet connection.

Tonight, when the bands open after sunset, I’ll experiment more 🙂🙂

#hamradio #swl #rfengineer

as it turns out, a local distributor actually had NOS ...

2026-05-09T14:25:00Z

In reply to nevent1q…yltm
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as it turns out, a local distributor actually had NOS 🤷🏼‍♂️🤩

Next step in my vintage SWL loop #antenna, the amplifier. The ...

2026-05-09T09:08:05Z

Next step in my vintage SWL loop #antenna, the amplifier. The design is really simple and I’m using vintage BF494 and BF451 transistors 👴🏻☺️
#hamradio #swl #rfengineer

The all time classic 555 timer turns 55y this year, originally ...

2026-05-05T08:10:13Z

The all time classic 555 timer turns 55y this year, originally released by Signetics in 1971.

Lets celebrate by building a classic 555 circuit: the astable multivibrator 🥳🙂

#electronics #electronicsengineering #rfengineer #hamradio

Connector savers are something you might want to use with your ...

2026-05-01T07:22:10Z

Connector savers are something you might want to use with your precious gear - in this case, for my R-8600 receiver ☺️☺️ #rfengineering #rfengineer #hamradio #SIGINT

Yah, occasionally you bump into them, as I did now ☺️

2026-04-30T07:25:01Z

In reply to nevent1q…62gw
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Yah, occasionally you bump into them, as I did now ☺️

Found a cheap batch of the BLK-89-S+ DC Block from #minicircuits ...

2026-04-29T20:51:24Z

Found a cheap batch of the BLK-89-S+ DC Block from #minicircuits - wondered if they were usable at near-VLF frequencies (they’re specified from 100kHz-8Ghz).
They turned out quite acceptable 👍🏼🙂🙂
I don’t need that many, at all 😂, but it was a bargain and I’ll likely sell some of them once I’m done with the tests.
Amazing you can make an almost flat frequency response that wide 😳 They’re NOS from 2013, but they don’t seem to age, shelf life is ‘eternal’ on these devices ☺️

#hamradio #rfengineer #vlf

Inspired by a 26y old article, I’m building a small loop, which ...

2026-04-26T20:07:15Z

Inspired by a 26y old article, I’m building a small loop, which with a suitable amplifier, might turn into a decent shortwave/BC antenna ☺️
#hamradio #rfengineering #rfengineer #shortwavelistening

Using my aging #buspirate 3.6 to read out a 24C02 in a defunct ...

2026-04-19T09:23:57Z

Using my aging #buspirate 3.6 to read out a 24C02 in a defunct kitchen scale.
It turns out it was surprisingly full of data 😳 Most of it likely calibration, but maybe also some intermediate stuffs since the chips write protection was permanently disabled.
Anyway, I just ordered a version 5 buspirate, seems like a decent upgrade 🤓 #EE #hardwarehacking #electronicsengineering

I bought a microscope with a HD camera 😄Any recommendations ...

2026-04-16T17:02:43Z

I bought a microscope with a HD camera 😄Any recommendations for camera SW that runs on a Mac? Need to be able to adjust gain, contrast, illumination(sensitivity), all that. Maybe do a bit of processing as well, but most importantly, it has to be simple. Total microscopy beginner here 🤷🏼‍♂️😂

I was told that it was new in the sense that ‘the N-Conn had ...

2026-04-15T15:23:24Z

In reply to nevent1q…kd6k
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I was told that it was new in the sense that ‘the N-Conn had never been used before’… I trust this, the person had no reason so say otherwise 🙂

One of those “it’s you or the dumpster” moments… How ...

2026-04-14T20:19:29Z

One of those “it’s you or the dumpster” moments… How could I possibly reject that? 🤷🏼‍♂️🤭

#rfengineering #rfengineer #hamradio

Wasn’t my radio, so I don’t know the history behind it, but ...

2026-04-14T18:57:51Z

In reply to nevent1q…7cpk
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Wasn’t my radio, so I don’t know the history behind it, but generally I use connector savers on my most precious gear ☺️

not my radio but yes, that was my first reaction as well (PL ...

2026-04-14T18:24:45Z

In reply to nevent1q…a6nm
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not my radio but yes, that was my first reaction as well (PL insertion). I have N ‘connector savers’ on some of my radios and more precious instruments. Just in case ☺️

Actual reason is unknown, it didn’t come out of my radio, but ...

2026-04-14T18:22:34Z

In reply to nevent1q…sngt
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Actual reason is unknown, it didn’t come out of my radio, but yes, that was my first reaction as well 🙂

Well that’s not supposed to happen 🤷🏼‍♂️😂 Came ...

2026-04-14T17:59:05Z

Well that’s not supposed to happen 🤷🏼‍♂️😂

Came from a brand new radio - I guess their quality control failed, - or caused it 🙂

#hamradio #tfengineer #rfengineering

God I love logperiodics 🥰 Such a fascinating structure - I ...

2026-04-10T21:08:22Z

In reply to nevent1q…x992
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God I love logperiodics 🥰 Such a fascinating structure - I have an alternate mail address: logperiodic@xxx.yyy 😂 I have several of them, some even calibrated (gain and AF)

the D3000 certainly wasn’t cheap, but I’m glad I got it. Plan ...

2026-04-10T20:53:35Z

In reply to nevent1q…x992
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the D3000 certainly wasn’t cheap, but I’m glad I got it. Plan to use it with my R-8600 and a Fobos SDR 🙂

exactly 😎

2026-04-10T20:25:36Z

In reply to nevent1q…7p9m
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exactly 😎

I recently got a R-8600, so I figured I could justify this and ...

2026-04-10T20:07:31Z

In reply to nevent1q…uv2p
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I recently got a R-8600, so I figured I could justify this and some really good feed cable ☺️

This will go in the attic for that exact purpose, broadband ...

2026-04-10T19:50:30Z

In reply to nevent1q…w2y6
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This will go in the attic for that exact purpose, broadband monitoring ☺️

OMG we need an IKEA name!!! Here’s one: BREDBAND (broadband) ...

2026-04-10T19:44:24Z

In reply to nevent1q…vvay
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OMG we need an IKEA name!!! Here’s one: BREDBAND (broadband) 😂😂😂

Diamond D3000 #hamradio #SIGINT ...

2026-04-10T19:22:02Z

Diamond D3000
#hamradio #SIGINT

I need a Bias-T which covers a wide frequency area, but also in ...

2026-04-09T15:24:04Z

I need a Bias-T which covers a wide frequency area, but also in the low end, sub MHz range for my LW loop antenna with LNA. Saw this one and decided to give it a go. Formally specified to 200kHz it has a -1dB at 100kHz which is really good 🤩
Below that it drops fast but that’s ok for my applications.
And I can use it for hydrogen line (1420MHz) experiments as well, win-win 🏆

#rfengineer #hamradio #testandmeasurement #rfengineering

I did exactly that before I shot the video. It’s gravity 🙂

2026-04-03T12:13:38Z

In reply to nevent1q…attq
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I did exactly that before I shot the video. It’s gravity 🙂

those were the days 🥰 That was (likely) due the the earths ...

2026-04-02T07:24:58Z

In reply to nevent1q…hl6u
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those were the days 🥰 That was (likely) due the the earths magnetic field, and not a gravitational pull of the electron beam ☺️

Did you know that crystal oscillators are orientation dependent? ...

2026-04-01T19:35:25Z

Did you know that crystal oscillators are orientation dependent? Well they are 😎

Albeit in the milliHz range for a 10MHz OCXO, the frequency change is completely measurable when you rotate the unit and change the crystals reference to earths gravity 🙂🙂

#rfengineering #hamradio #testandmeasurement

Dream come true - enjoy a decent ‘defoiling’ and power-up of ...

2026-03-25T20:15:52Z

Dream come true - enjoy a decent ‘defoiling’ and power-up of my new #ICOM IC R-8600 🥲🥳

#hamradio #SWL #SIGINT

below 5dBcat 😂

2026-03-19T16:07:39Z

In reply to nevent1q…fx92
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below 5dBcat 😂

Right after birth, the still blind ‘horn kitten’ seeks out a ...

2026-03-19T15:33:01Z

Right after birth, the still blind ‘horn kitten’ seeks out a place to hide, typically a horn antenna.
The antenna and cat forms a symbiosis, and grow together, until finally, around age 2, a fully grown cat and an L-Band horn settles a life long relationship.

Occasionally two kittens settles in the same horn, forming a ‘Vivaldi pair’ and they’ll stay together like that for the remainder of their life.

This picture is extremely rare - as David Attenborough was once quoted, “It’s absolutely astounding”

#antennas #kitty #rfengineering

you’re welcome, it was harder than I thought (although in ...

2026-03-11T21:12:08Z

In reply to nevent1q…rks5
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you’re welcome, it was harder than I thought (although in principle quite simple), because it’s so sensitive to external noise 🙂 But it shows that you can actually prove at home, that light has particle behavior - I find that really cool 😎🤩

Driving a LED at sub-nA currents, allows me to measure single ...

2026-03-11T19:02:43Z

Driving a LED at sub-nA currents, allows me to measure single photons, thereby proving that light acts like small energy bunches 👌🏼😎😎

See my previous video if you want to know more about the setup and the PMT (Photo Multiplier Tube)

#stem #physics #testandmeasurement #quantumphysics

+1 right back at you. 🙂

2026-03-11T15:43:00Z

In reply to nevent1q…exu3
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+1 right back at you. 🙂

Oh my… I finally have one… 😳🥲 What’s up with my luck ...

2026-03-11T09:46:13Z

Oh my… I finally have one… 😳🥲

What’s up with my luck these days 😃

#rfengineers will know what this is all about 🥰

#bestdayever #rfengineer #rohdeschwarz

absolutely 💯 One of the four threads is busted but I can fix ...

2026-03-11T06:14:33Z

In reply to nevent1q…z6xy
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absolutely 💯 One of the four threads is busted but I can fix that (they go into a closed cavity, not part of the chamber)

Lucky me! 😃 Came across this beauty, mint condition, at a ...

2026-03-10T21:12:00Z

Lucky me! 😃

Came across this beauty, mint condition, at a price which left little debate 🤌🏼🤩

I finally have a calibrated horn antenna 🥲

#rfengineering #hamradio #testandmeasurement #testgeartuesday

Purely out of instinct and how I understand nature, I’d expect ...

2026-02-22T11:28:15Z

In reply to nevent1q…2jej
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Purely out of instinct and how I understand nature, I’d expect it to decline when cooled. Things tend to slow down a lot at cryogenic conditions, but that’s just a gut feeling 🙂

I was asked elsewhere about any influence of external light, ...

2026-02-22T10:57:53Z

In reply to nevent1q…fw9q
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I was asked elsewhere about any influence of external light, here’s my answer 🙂

Built a test setup for my PMT tube, allowing me to bias an LED at ...

2026-02-22T10:55:03Z

Built a test setup for my PMT tube, allowing me to bias an LED at really low currents, hopefully catching single photons, or at least a very low count 🙂

Photo Multipliers are insane devices! 🤷🏼‍♂️🤯

This video is meant to explain the setup, stay tuned for my next video where I do actual measurements 🙂🙂

#stem #physics #electronicsengineering #testandmeasurement #quantum

That’s extremely kind (and trustworthy) of you 🙏🏼 I’m ...

2026-02-18T20:36:17Z

In reply to nevent1q…9f8f
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That’s extremely kind (and trustworthy) of you 🙏🏼 I’m exploring a bit of options here - then I might get back to you 🙂 After all, it’s ‘just’ a (photon counting) experiment in my private lab ☺️ Cheers

Regular frequency counter often have issues with non-periodicity, ...

2026-02-18T18:31:36Z

In reply to nevent1q…nqwc
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Regular frequency counter often have issues with non-periodicity, that’s why I’m looking for a real counter

oh that would cost me a vital organ… 😂 But I got a ...

2026-02-18T18:30:27Z

In reply to nevent1q…cqqw
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oh that would cost me a vital organ… 😂 But I got a suggestion elsewhere, that a discrete counter (74AC4040) could do it, then simply have some Arduino thingy do the math…

Fellow EEs, I need a universal counter which can totalize pulses ...

2026-02-18T16:11:24Z

Fellow EEs, I need a universal counter which can totalize pulses like these over a set time, fx. 1 second, and do statistics over over subsequent measurements… Any ideas? Amount of pulses during the test window is of stochastic behavior, but ranges from 20-40 per second to several thousands… Any ideas? 🙏🏼🙂

For an upcoming experiment, I need to know how accurate my ...

2026-01-24T19:21:45Z

For an upcoming experiment, I need to know how accurate my #Keithley 2400 is at nA outputs (God I absolutely love that box… 🥰), but I also wanted to see how well my 6.5digit GDM-9061 multimeter tagged along..

Enter the HP 3458A… 💪🏼😎

Connected them all in series and although the set point on the 2400 is a bit off from reality, it’s own current measurement is bang on. At 20nA 🤯😃 And the 9061 multimeter was in agreement as well, even at such low currents.

Ready for next step, stay tuned 😎😎

#electronics #testandmeasurement #rfengineer #electronicsengineering

Yup, I know the principle 🙂 Think I’ll stick with light for ...

2026-01-24T07:46:07Z

In reply to nevent1q…6ev5
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Yup, I know the principle 🙂 Think I’ll stick with light for now 👍🏼

😂 We’ve all been there ☺️ 73s

2026-01-20T17:25:58Z

In reply to nevent1q…vwza
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😂 We’ve all been there ☺️ 73s

Get a Siglent SDS1202X-E, when you’re ready to ramp up. It’s ...

2026-01-18T17:33:58Z

In reply to nevent1q…07cy
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Get a Siglent SDS1202X-E, when you’re ready to ramp up. It’s excellent value for money and really easy to use.
I had one once - sold it for a 4CH upgrade, but it’s a really decent allround scope.
You’ll hear ppl say ‘no one buys 2CH anymore’ but that’s BS. 4CH almost doubles the price and unless you’re really into the hobby (or moving towards a professional status), 2CH is by far sufficient. Best of luck 🤞🙂🙏🏼

very few, even vintage, scopes are single channel, but they’re ...

2026-01-17T10:10:01Z

In reply to nevent1q…crtw
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very few, even vintage, scopes are single channel, but they’re out there 🙂

At the night of the legendary capacitor explosion we also hosted ...

2026-01-17T08:54:47Z

At the night of the legendary capacitor explosion we also hosted a BYOD Oscilloscope night, where ppl could bring their instruments and learn more about them, common pitfalls, how to do basic measurements, more advanced stuff, etc.

Surprisingly many electronics enthusiasts don’t have an oscilloscope, and even more surprising, many don’t really know how to use the instrument they have.

The evening opened many new doors to the participants - I think everyone were happy 😃

#hamradio #electronics #electronicsengineering #rfengineer #testandmeasurement

in fact, you could argue it a rough day at work ...

2026-01-17T08:24:47Z

In reply to nevent1q…s88f
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in fact, you could argue it a rough day at work 🤷🏼‍♂️😂

not as bad as you would expect, it was a dried out paper ...

2026-01-16T15:09:50Z

In reply to nevent1q…8g4h
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not as bad as you would expect, it was a dried out paper capacitor 🙂

😂

2026-01-16T15:08:54Z

In reply to nevent1q…920g
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😂

certainly was 😆🎉

2026-01-15T07:24:59Z

In reply to nevent1q…sfn8
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certainly was 😆🎉

paper from the looks of it 🙂

2026-01-13T21:56:04Z

In reply to nevent1q…e2px
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paper from the looks of it 🙂

oh yes 😂 Once we established that everyone was ok, and we’d ...

2026-01-13T21:25:18Z

In reply to nevent1q…mkjh
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oh yes 😂 Once we established that everyone was ok, and we’d cleared the smoke, I looked at the three guys: they were covered in it! 🤣

Suddenly a loud bang from the lab at the local #hamradio club ...

2026-01-13T21:14:06Z

Suddenly a loud bang from the lab at the local #hamradio club ‼️ 💥🤯

Luckily nothing happened to the people in there, but I guess it’s safe to say that this vintage capacitor decided to quit its job 😂

Always wear safety glasses 🥽 when testing and troubleshooting #electronics, especially if it’s vintage gear where you have no knowledge of its state and health☝🏼

#electronicsengineering #vintageelectronics #vintagerepair

I bought a #Hamamatsu H7828 photomultiplier module, a ‘photon ...

2025-11-27T21:17:19Z

I bought a #Hamamatsu H7828 photomultiplier module, a ‘photon counter’. They’re insanely sensitive 😳

Seller knows what they’re dealing with and sealed it nicely in aluminum tape.

I left the tape mounted and put it in a box to screen the ambient light in my lab (which was already dimmed), then powered it on. It shows a ‘dark count’, noise that produces a certain level of ‘background’ pulses. Then I opened the box, just a little. And it’s visible!! 😳😳

A few photons, not many, still makes it to the detector, despite the aluminum tape sealing, it’s insanely sensitive 🤯🤯

I need to find a way to count the pulses and do some statistics on it, stay tuned for future experiments 🤓

#electronicsengineering #engineer #physics #stem #photon #photoncounting