🎓 Doc Freemo 🇳🇱 @freemo@qoto.org

I am making tons of progress on my #OSS . #FOSS APRS project called #Digipex.

I got an igate relay hosted (this will be neccesary to ensure we can get dup packets):

https://igate.digipex.io

I got a web-app going that will display allt he clients on the map and give some statistics/status info:

https://hub.digipex.io

I also have the most important part, working code that talks to the radios and routes / rewrites packets. Right now it can send/receive, digipeat, and gate to and from the igate.

The code for digipex is here: https://git.qoto.org/digipex/digipex

And you can see some information about my particular digipex node here:

https://hub.digipex.io/views/overview.php?id=43449

The picture below is of a microcomputer (like a raspberry pi, its a khadas) running digipex and showing the packets it deals with on the miniature screen.

#APRS #Ham #HamRadio #Radio #Rf

Well I managed to have a productive day yesterday. I got APRS-IS/IGATE working on my APRS client as well as fixed the pathing so it inserts the stations callsign.. Its been working live all night. Already seeing the new stats on the website!

Station info: https://aprs.fi/info/a/WI2ARD-1

#Radio #RF #HAM #HamRadio

I just bought some really nice domains for my #APRS project:

aprs-x.com (also got .org)
axps.org

I plan to use aprs-x for the protocol specification itself and axps for the software I am writing that will run it.

#Ham #HamRadio #EE #AmateurRadio #AmaturRadio #Radio #RF

Dude this solar cycle is getting crazy!!

#ham #hamradio #physics #space #radio #rf #sun #SpaceWeather

We had quite a large flare today!

#ham #hamradio #physics #space #radio #rf #sun #SpaceWeather

What sort of glue is best for fixing broken #HamRadio equipment and antennas? ... why Elmer's Glue of course!

#RF #Radio #AmateurRadio #HAM

In 12 hours my radio beacon was heard directly by a few fairly long distance stations for the frequency I'm working:

95 miles x2

104 miles x3

156 miles x1

92 miles x2

Sweeet!

You can see for yourself here:

https://aprs.fi/info/a/WI2ARD-1

#EE #Radio #HamRadio #AmateurRadio #Electronics #RF

Just saw some minor VHF skip or something... my beacon just traveled 155 miles to virginia from my roof... thats unusually far for 2m VHF....

#EE #Radio #HamRadio #AmateurRadio #Electronics #RF

I cant express how excited i am to have my station back up and runni g again off my own custom software... seriously this is awesome! Been waiting 2 years to finish this project!

#EE #Radio #HamRadio #AmateurRadio #Electronics #RF

Managed to bri g the software i was writinf for #APRS back online at my station. It is working perfectly again. Beacons are successfully being sent and digipeating is working.

You can see the screenshot of the control terminal attached. You can watch the packets live here:

https://aprs.fi/info/a/WI2ARD-1

#EE #Radio #HamRadio #AmateurRadio #Electronics #RF

My VHF APRS beacon has now officially went live again after 2 years! You can track its packets and location here:

https://aprs.fi/info/a/WI2ARD-1

#EE #RF #Radio #HamRadio #AmateurRadio #Electronics

There has been a lot of discussion lately, much of it just plain incorrect, about the relationship between resonance and antenna efficiency. Many incorrectly claim that resonance has nothing to do with antenna efficiency at all, similarly others incorrectly claim that resonance is a direct indication of efficiency. Neither of these statements is true. The reality is that resonance does have a significant impact on how efficient your antenna is, but the relationship is highly non-linear and depends on many characteristics.

Below I have attached a chart hat plots out the total radiation resistance (R_r) vs the measured input resistance (R_in) of a dipole. Efficiency is just R_r/R_in. In other words an efficient antenna will have 100% of its resistance as radiation resistance, and R_in is **always** larger than R_r (since it is essentially ohmic resistance plus radiation resistance). When these two numbers differ significantly an antenna is inefficient. The source for the chart below is here and it gives much of the math if you want a deeper dive:

https://nptel.ac.in/content/storage2/courses/108101092/Week-2-Dipole%20Antenna.pdf

What is important to note here is that at anti-resonance we see a **huge** R_in value and a small R_r value, this means an anti-resonant antenna will have very high losses. Keep in mind the graph is very hard to read for the values <0.5 in length because the resolution isnt high. But there is significant divergence there as well. Notice at ~5/8ths wavelength antenna would exhibit very significant internal ohmic losses due to heat.

#hamradio #rf #radio #ee #electronics #electricalrngineering @Electronics

lolol

#Radio #RF #HamRadio #Ham #EE

I want to open a #HamRadio store called "Perfect Example". It sells large antennas for your roof that all tune up to a perfect 1:1 SWR but have 0% effiency.

ham radio operator's credo:

1. Be a jerk to everyone you meet

2. Make assumptions about how things work based on the first explanation someone gives you and never change your mind or learn anything more about it for the rest of your career in HAM radio.

3. if someone gives you advice contrary to #2 call them names and insult them until they go away

4. Never do math, numbers are a lie. As long as you can hear someone talking in your radio then your assumptions are validated.

5. Under no circumstances should you actually learn how things work. Simply quote people with credentials and insist your misunderstanding of the quoted text is the only correct one. If someone disagrees with you remember your credentials are automatically the same as the authors, so you are right.

6. Make it a point to never understand the purpose or intent of FT8 and anytime you see anyone mention it make fun of them for not being a real HAM

7. CW is the only acceptable mode of operation, everything else is contrary to the spirit of HAM radio.

8. Only people over the age of 90 are allowed to be HAM radio operators, everyone else is ruining the hobby.

9. Making a joke of any kind should be treated exactly the same as a personal insult. You now have the right to respond to the person as rude as you'd like

#RF #HAM #HamRadio #amateurRadio #EE

A wonderful site showing a few different types of radio signal **refraction**. Important to note what you are seeing here is totally different from the effects you get from HF radio frequencies and occurs with VHF and UHF as well. Its why generally line-of-sight frequencies like UHF can sometimes go some ways over the horizon.

https://www.dxinfocentre.com/propagation/tr-modes.htm

#Radio #RF #Ham #HamRadio #AmateurRadio #EE #Electronics #Science #STEM @Science

Hacked together an ultraportable HF antenna system to work well between 3.5Mhz - 200 MHz (80 meters - 2m) frequencies. Basically took a coil loaded GRA-1899T antenna with telescoping antenna, added some off-the shelf BNC adapters and did some minor hacking. To make it work I had to remove the center connector from two of the BNC adapter s(marked with an X in the diagram). Then added a short-circuit BNC connector, which connects the otherwise floating center connector from the bottom half to ground/shield enabling the counterpoise. Added two additional telescoping elements for the counterpoise and we have a complete system.

The thing I like about the approach is the modularity. For example I can remove or add normal t-connectors to change the number of counterpoises used. The setup pictured uses 2 counterpoises but it would be trivial to setup 1 to 4.

Also the short circuit connector (pictures here as the black and teal connector with the short circuit in it) can allow me to do multiple things if i want to get more complicated. For example if I want to remove the short circuit I can replace it with coils or capacitors for additional tuning. I can also leave it as is but connect an earth ground to it to improve the effectiveness of the counterpoise.

A final note, the loading coil attached to the radiating part of the antenna has a jumper with 6 different positions. This lets you manually adjust the size of the loading coil for different frequencies. Fine tuning is accomplished by changing the length of the antenna itself.

#Science #electronics #RF #radio #Amateur AmateurRadio #HAM #HAMRadio ## @Science

Woot, my Lab599 TX-500 SDR transceiver arrived today! Powered it up and tested her and she works great. Now just need to get a mobile setup together and time to test her on a trail somewhere.

#hamradio #RF #EE #radio

Some pictures of my APRS station brought back to life. Currently being heard in Ireland, Canada, Germany, and Washington state (I'm on the opposite coast).

#ham #hamradio #radio #RF #EE #Electronics #AmateurRadio @Science

Sweet, just brought back up my APRS radio station transmitting on both VHF and HF frequencies. Looks like it is working great I am being heard in both Ireland and Canada on the HF side!

Can't wait to get back to coding PEAK (the APRS software I run that runs a next gen version of APRS I am developing).

https://aprs.fi/info/WI2ARD

@Science #ham #hamradio #radio #RF #EE #Electronics #AmateurRadio