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Oznaka: ham radio

Real characteristics of 868 MHz Band Pass Filter from AliExpress

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868mhz Band Pass FilterUsual source of components for Meshtastic node builders are sites selling goods coming from China. There is always concern on quality of products coming from there. Here is measurement of 868 MHz Band Filter I did on item I got from AliExpress.

Actual filter is PCB SMD component. The rest is just PCB that allows attaching SMA male and SMA female connectors to it and everything is wrapped in transparent heat shrink tube. Everything is pretty small: 35 x 8 x 7 mm. It is meant to be used by inserting it between 868 MHz device and antenna.

Claimed characteristics:

Center frequency: 868 MHz
1dB bandwidth: 10 MHz
Tape interpolation loss: < 2.0 dB
Out-of-band suppression:
> 42dB@700 MHz
> [email protected] GHz
Impedance: 50 Ohms
Maximum load power: 20 dBm(100mw)

Here is what I measured using NanoVNA:

Center frequency: 868.503 MHz
1dB bandwidth: 10 MHz
3dB bandwidth: 14.1566 MHz
6dB bandwidth: 15.6301 MHz
Tape interpolation loss: 2.709 dB
Impedance: 49.1-j5.78 Ohms

You can check graph:

869mHz Band Pass Filter -Measurement

What is conclusion? […]
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Multiversum Mind – Hunting For DX (amateur radio song)

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I always wondered why there is not much of music of amateur radio thematic. I had few ideas of amateur radio songs and as I am bit skilled creating lyrics I am totally helpless on creating music so all those ideas just stayed on paper.

When I learned about AI creating music i saw it as an opportunity. So I took one of my lyrics and tried to give it musical life. My goal, fo course, is not to create super smash hits, but just stuff nice to listen.

So I did some experimenting using Suno AI and created number of music versions for the same lyrics. […]
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Morse Code Sound Machine

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Wanted to create something that will introduce Morse Code to kids. It had to be simple and looking like a game, so I ended up with making Morse code Sound Machine.

Idea is that kids enter their names and then listen how it sounds in Morse Code and also Amateur Radio.

There is animation of sending Morse code and options to change speed and tone frequency. I guess that is enough to keep them interested for a while.

Application is written in plain JavaScript and can be run in any web browser.

Morse Code Sound Machine source code is available at GitHub. […]
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Ham On Key (lyrics)

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Ham On Key

That day I was turning dial through the band
My radio was squeaking sounds like a sand.
I could hear some local rag chewing hams
And they talked that bands are open nice.

Oh call
CQ CQ CQ some more time.
Get my answer and I’ll finally be fine.
You, make me, make me, make me wanna cry
And now I beg to hear you call just one more time.

So I say,
Wait for me,
wait for me,
wait for me
Oh, oh, oh.
I never worked no one from your DX zone before.
I say,
beam for me,
beam for me,
beam for me
ay, ay, ay
And if you hear me, happiness will make me high. […]
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Kako proveriti ispravnost SWR-metra?

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Dopao vam je šaka neki SWR-metar pa treba da ga proverite da li je ispravan i tačan. Kako to uraditi?

Metod 1: Poređenje sa poznatim antenama

Ako imate antene za koje znate kakav je SWR, prosto priključite SWR-metar u kolo sa antenama, izmerite SWR i ako je tu negde kao što znate da treba da bude, to je to.

Metod 2: Poređenje sa poznatim instrumentom

Povežite nepoznati SWR-metar u antenski sistem zajedno sa poznatim (proverenim). Probno emitujte na frekvencijama koje su vam interesantne i pratite da li nepoznati SWR-metar daje slična pokazivanja kao i onaj provereni. Ako je tu negde, onda je ok. […]
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