ADS-B DIY Antenna

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ab cd

Senior Member
Sometimes it's necessary to give the full path, like this 'sudo /sbin/reboot'. Might help.
I recall that sudo/sbin/reboot is prefered over sudo reboot as the pi will prepare itself first and execute a clean reboot so that is why I used it in my crontab every hour, on the hour,every day, every week.
The pi2 unit running d1090 + 4 feeders completes the reboot in 20-25 secs typically.
I know it probably has log entries building for this timed task in var/log and i have not bothered to log rotate but i have a 32gb class10 sd and to date "df" tells me i have used 21% of the space available s i have some time to go before capacity is a concern.
Problem was not with path, it was due to typing alphabet o instead of numeral 0.
After changing alphabets o o by numerals 0 0 in entry 0 0,6,12,18 * * * sudo reboot, the RPi started rebooting as scheduled.

When a command is run as root, files inside the sbin folder have a higher priority than the other folders in the path.
That is why when command sudo reboot is given, sudo automatically chooses /sbin/reboot.

Later addition:
If you check your sudoers file in /etc, you will find the default path given there.
Code:
pi@raspberrypi ~ $ sudo cat /etc/sudoers
#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults        env_reset
Defaults        mail_badpass
Defaults        secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

# Host alias specification
# User alias specification
# Cmnd alias specification
# User privilege specification
root    ALL=(ALL:ALL) ALL

# Allow members of group sudo to execute any command
%sudo   ALL=(ALL:ALL) ALL

# See sudoers(5) for more information on "#include" directives:

#includedir /etc/sudoers.d
pi ALL=(ALL) NOPASSWD: ALL
pi@raspberrypi ~ $
 
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Marty Becker

New Member
My numbers are very different between PF and FA. I see a lot more on PF than FA. There's a thread on FA where people were comparing their stats. I can't find it right now. The FA staff explained how they count differently on each site. If I locate the thread I'll post a link here.

Edit: I found the thread. It was a comparison between FR24 and FA, but I mentioned my PF stats in it. http://discussions.flightaware.com/ads-b-flight-tracking-f21/fr24-and-flightaware-stat-comparison-t24640.html

Yet another edit: Ah, my memory is faulty. It's just FR24 vs. FA.
I noticed the same thing regarding FA & PF counts. I asked the question in this thread I started, but no answer.

http://forum.planefinder.net/threads/how-are-counts-derived.271/

Marty
 

jepolch

Active Member
Coax and brass tube
View attachment 2181

4 elements
View attachment 2183

Solder
View attachment 2179

Closeup
View attachment 2180

Decouple sleeve 1/4 wavelength
View attachment 2182
Very nice work, Bram. What is the distance (gap) from one copper sleeve to the next one? I want to make one of these when I find the copper tube. There used to be a craft store nearby that had absolutely anything you wanted, but they closed. Now I don't know where to get the tube, except online.
 
Did you use LMR-400 coax? I bought a brass tube on Amazon. I tried using RG6 and the dielectric insulation is way too small when I put it inside the tube. http://smile.amazon.com/gp/product/B000H9JLO0
@jepolch , Send a quick email over to Davis RF stating your dielectric diameter size requirements of 0.22 inches (5.8mm), they will have a coax cable for you and they sell by the foot so it wont cost the earth.
They are main agents for Times Microwave, Andrews etc.
Superb service from Davis,I have used them for years, second to none IMHO.

http://www.davisrf.com/index.php
 

jepolch

Active Member
@jepolch , Send a quick email over to Davis RF stating your dielectric diameter size requirements of 0.22 inches (5.8mm), they will have a coax cable for you and they sell by the foot so it wont cost the earth.
They are main agents for Times Microwave, Andrews etc.
Superb service from Davis,I have used them for years, second to none IMHO.

http://www.davisrf.com/index.php
Good idea, but I've already ordered four feet of LMR-400. The link that Bram gave for the plans for the coco say to use LMR-400 and 5/16" brass tube, which is what I have. The reason I asked Bram if he used LMR-400 is because in the pictures I've seen of LMR-400 the center conductor looks thicker than the conductor in Bram's photos. Hopefully I'll be able to make one using the parts I bought.
 

TomW

Member
Good idea, but I've already ordered four feet of LMR-400. The link that Bram gave for the plans for the coco say to use LMR-400 and 5/16" brass tube, which is what I have. The reason I asked Bram if he used LMR-400 is because in the pictures I've seen of LMR-400 the center conductor looks thicker than the conductor in Bram's photos. Hopefully I'll be able to make one using the parts I bought.
Looks like a perfect match. I'm ordering some too!
Tom6-19-2015 8-34-39 AM.png
 

jepolch

Active Member
Speaking of coax, I'm thinking of upgrading my feedline to the antenna. I've read that Belden 1694A is the best RG6 coax. Any opinions? I have heard of people using LMR-400 as a feedline, but that would get pretty expensive for a 50 foot run. Even the Belden is not cheap.
 
Watch out on the VF with brass tubing on a stripped 50 ohm LMR400 guys,
You could treat yourself and try to make a coco with the mother of coaxials, Andrews Heliax LDF5-75 (a 75 ohm cable for a 75 ohm job),if you can get it..the 50 ohm (LDF5-50) is more popular.
No faffing with tubing as its already in the cable makeup..Here you will be in the company of the elite of coaxial cables, Andrews are always batting at the top of their game on heavy duty microwave feedlines but, a caveat..connectors will put a serious dent/ouch in your wallet.
A hardline N connector is anything between $75-$125 USD, yes thats each !
I dont trust my weak soldering skills with a connector of this expense.
I would recruit xforce,jepolch,tom or bramj..well worth the return postage !
Davis RF will have and sell this by the foot I imagine.

Off topic, To model maker extraordinaire @jepolch,
I found a very interesting page via flightaware about the demise of the Russian space shuttle program, made very sad reading..what a travesty.
http://gizmodo.com/these-are-the-sad-remains-of-the-soviet-space-shuttle-p-1710827956
 
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ab cd

Senior Member


AndrewHeliax.png


The cable "Andrew Heliax" will make a very sturdy CoCo

LDF4-50 specs:

Outer Conductor: Copper
Inner Conductor: Copper-Clad Aluminum
Diameter over Jacket, 0.63 inch /16 mm
Diameter over Copper Outer Conductor: 0.55 inch / 14 mm
Diameter Inner Conductor: 0.189 inch / 4.6 mm

Impedance: 50 ± 1 ohms
Maximum Frequency: 8.8 GHz
Foam Dielectric
Velocity Factor: 88%

AndrewHeliax225.png

 
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Hi ab cd ,
Yeah , robust cable indeed.
The LDF5-xx series is bigger again,a 7/8 inch diameter,not for the faint of heart or light of wallet !
I would love to see xforce trying to bend that 90 degrees back on itself like he does with his wire tricks, I bet he could do it too !;)
 
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