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Messages - Quinta

Pages: [1] 2
The RF Workbench / Re: 4096 beacon goes wild soon :)
« on: July 29, 2023, 2016 UTC »
Looks like previous beacon is dead. I never heard it at home, his antenna was badly tuned, and looks like his solar panel see sun only half a day. So i made a new one. With L-network for working with endfed wire. Software much smarter. Attiny85 control everything. Masure voltages, if accumulator voltage lower than critical he try charge battery with 8% PWM to prevent reset controller when solar battery shorted by deep discharged accumulator. Also with telemetry after main message he transmit  not very important information about beacon, six phrases, for example tranmitter power with one message, accumulator type with next message, in cycle. Antenna - 0.5 mm stainless wire.
And most important... i can hear it at home, on my WEBSDЯ, very weak, but better than nothing.
His marker - three dits with different length. 0.075, 0.1 and 0.15 secondswith pauses between dits 0.05 sec, marker period 3 sec. Transmission every 6 min.
later i try to tweak antenna performance.


But i should say what mini-whip is reduced variant of active whip for HF, like RFT KAA-1000 which was used by Bundeswehr in 80-s.

The RF Workbench / Cheap beacon construction examples
« on: July 26, 2023, 0042 UTC »
I made couple similar beacons this summer, and want to share their construction.
Transmitters are primitive, 190-200 mwt output with 3.3V power from LiFePo cell, almost 500mwt with 6.3V from solar panel.
Charge current limited by solar panel, contoller only every 8 sec switch off charging and masure voltage on battery.
Controller - attiny85, voltage not stabilised, but limited with resistor and 4-5V zener diode. This circuit not draw power at night because maximum battery voltage is 3.5v. Attiny work with internal 1.1V reference voltage and internal rc generator, brownout level 1.8V Flashed via arduino as isp, with ATTiny Core for arduino. Actually program ismodified NicoVarg99 cw beacon, because program allow use not hardcoded text strings, so we can measure and send some telemetry. I only add voltages measuring and control charging circuit.
Boards covered with Plastic 71, bottom side of the boxes drilled for drainage and ventilation, because in closed boxes forms condensation.

Controller schematic

First beacon, 27.143MHz

Second beacon, 13.56MHz

Active loops should work better, because they almost not catch common mode noises. In my case when i install chinese mini-whip on window i can hear only very powerful stations, MLA-30 in the same place work beautiful. I hear amateurs, pirates, HF RDARA, HFDL signals from planes over China, while i live near Finland.

i think LNA instead of balun should work much better. Or aplifier like Chavdar Levkov amp.

The RF Workbench / Dual (multiple) frequency beacon
« on: July 25, 2023, 1955 UTC »
Because propagation changing from day to night i try to make dual frequency and simple transmitter for qrp beacon. I try diode commutator and it works.
Beacon powered from 5v 350 ma solar panel and 3V 6A/H lifepo accumulator. Because my controller know voltage on solar panel he will switch frequency on twilight and dawn, it even can be done by primitive voltage comparator, without any programming

Software / OpenWebRX+
« on: July 20, 2023, 2309 UTC »
Almost year ago i set up this websdr server, and i think he is awesome.
1 Opensource, and fast developing software.
2 Can be installed in ubuntu and debian on aarch64 or amd64 simply, via some commands on terminal, or as Docker container, or have prepared sd card images for raspberry pi
3 Very simple settings via admin webpage, the only thing you should do in linuc CLI is a adding websdr admin.
4 Really awesome: support a lot of sdr receivers: rtl-sdr, hackrf, airspy, sdrplay, HPSDR (hermes), USRP, Bladerf.
5 Can decode online a lot of amateur and professional digimodes, from CW to HFDL, and meteofax. In some modes, like HFDL, AIS or JS8 he can display received coordinates on map.

6 Have a map which can display also other websdr, kiwi or openwebrx websdrs.
7 Average load with single user only 25-30% higher than pa3fwm websdr on same hardware. Simultaneously working 5 rsp1a with 8mhz bandwidth + hackrf with 20mhz bandwidth eat approx 60% resources of my old Xeon E3-1270v3.
8 You can set some receivers which can work simultaneously, or set some "profiles" which set frequency, bandwidth, gain and lot more settings for single receiver, and swith between them (of course this is problem for more than 1 user on server).
9 Have free tuning option, but with some trickery.
So we have software which easy to install on almost any computer (include not raspberry singleboard arm, for example Orange pi and Rockpi), very agile and free to use.
The beauty of this project is that you can easy and cheap (you need only not very powerful computer and external ip) share your sdr with other people. Not need to buy relatively expensive and rare hardware or struggle with several configs for having only 2 megs of bandwidth in case of websdr.

My websdr

link http://hoshinokoe.ru:8073

The RF Workbench / Re: Common mode supression
« on: July 20, 2023, 2228 UTC »
My english still very bad, but i should tell here about my experiments.
Your English is good enough to write this, which is reasonably high. I can see that you paid attention in English class.  :)

I simply love to watch AVGN :)

So, after some measuring i make the best antenna transformer for receiving: magnetic transformer on N87 ring, relatively thin and big diameter, so capacitance between windings minimal.

The RF Workbench / Common mode supression
« on: March 18, 2023, 0935 UTC »
My english still very bad, but i should tell here about my experiments.
Common mode noise i measure between PC case and grounding in 9 floor building via 10:1 voltage divider - almost 13 volts.
My previos schmatic for CM supression. Miniature galvanic isolated 9:1 transformer instead of balun, second miniature 1:1 transformer near receiver
But in the big building grounding very noisy, almost like a mains power. So intead of classic long wire and grounding much better use a two random wires attached to balun.
Measuring of some variants.
Then i add a long, 30 cm common mode choke, made like a anode choke, but winded with two paralel wires, to reach maximum reactance.
I still not measure this long balun, but it seems t be its better then only miniature transformer.
Today i made a Austin tranformer for HF to measure its reactance for common mode.
Certainly reactance depends on design, bit this particular design has 4-5 db better common mode suppression in 50 ohm schematic compared with compact balun from aliexpress.
The only problem with austin balun - this is a magnetic transformer, so you can't use random ferrites ripped from vga cable chokes. And it has high leakage inductance, so losses in poorly designed austin transformer can ruin advantages of low winding capacitance.
Now i use "long" balun with my personal sdrs and parallel with web-sdr on my personal webpage.
For example - coastal station Skagen on 1700KHz, distance approx 1200km.
Yes, still bad but with classic amateur contruction in my case noise floor would be much higher

The RF Workbench / Re: Beacon Keyer hardware
« on: August 12, 2022, 2116 UTC »
Tiny85 can be flashed from arduino ide, i made 2 beacons with tiny85, and use internal reference voltage for voltages measuring.

The RF Workbench / Re: 4096 beacon goes wild soon :)
« on: August 06, 2022, 1235 UTC »
I little bit obsessed with beacons :)
Two of them intalled here https://www.google.ru/maps/@59.8563053,31.3976757,1917m/data=!3m1!1e3
Also i rework charging scheme, now if battery shorted or discharged scheme can't drop voltage and reset the controller
Hmm, i can't insert image from my home server, so i insert the links.
Here i receive beacon with ATS-20

The RF Workbench / Re: 4096 beacon goes wild soon :)
« on: October 22, 2021, 1443 UTC »
Device installed
Aaaand... i cannot hear it with my 8 meters random wire. But with ATS-20 and 20cm telescope i can hear it in the forest, 500m far from my home.
Antenna not tuned, i think i should made block with 2 stretchable tuning coils and install it between device and antenna.

The RF Workbench / Re: 4096 beacon goes wild soon :)
« on: October 15, 2021, 1751 UTC »
I roll in the forest today between 13.00 and 19.10, trying to find thick pine with a clearing on the south, for lighting solar battery.
But lost in this game. Also in ths road a lot of people. I know one more appropriate place, tomorrow i will go there. https://wikimapia.org/#lang=ru&lat=59.787507&lon=31.245375&z=14&m=w
Now i charging acid of beacon from PSU.
I translate comments in beacon sketch to english, and download sketch to pastebin

Some photos "Meanwhile in the forest"

A sign at the site of a village destroyed in ww2, there are 10 of them within a radius of 15 kilometers

Some roads really ancient. 17хх year

The RF Workbench / Re: 4096 beacon goes wild soon :)
« on: October 10, 2021, 0925 UTC »
I can install dipole from notrh to south. But not very high, 10-15 meters above ground, on the trees.

The RF Workbench / Re: 4096 beacon goes wild soon :)
« on: October 09, 2021, 1803 UTC »
He will be placed somewhere here
So, in north america he can be received only with websdr.
Also i use plastik-71 on pcb, 3 layers. It much better than epoxy.

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Item image   The ARRL Antenna Book 15th Edition, Second Printing, 1988