Air band J Pole Antenna, Bargain - RTL SDR Noise fixed

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Air band J Pole Antenna, Bargain - RTL SDR Noise fixed

Postby barrylewis1234 » Sun May 27, 2018 9:42 am

Hi all, just thought id share this with you.

For about a year now ive ben listening to Air Traffic using my RTL SDR and its supplied antenna, I mounted that upon the side of my house on a large metal plate, this worked ok and I didnt know any different.

I then built a J Pole from copper which works very very well. I made it from 22mm plumbing copper and used the calculator from this website https://m0ukd.com/calculators/slim-jim- ... calculator. This works amazing, im pulling in so much much more on the receivers, and very strong signals indeed.Its also pulling is poscag pagers at 151mhz really really well and a great improvment right across the band, not just in the aircraft stuff which ive tuned it to

If you decide to make a J Pole then get yourself one of these https://www.ebay.co.uk/itm/DIY-J-POLE-A ... 2659591355 this made the build much easier. I purchased a 10m PL259 coax lead and a SO239 to SMA converter for my RTL SDR receiver.

This same sellers sells J-Pole ready to use and at 29.99 I think thats a bargain, mine cost nearly that to make out of copper:

https://www.ebay.co.uk/itm/AirBand-Scan ... 2663737501

I also noticed theres always a slight interferance on my RTL SDR so I set about fixing this. Heres what i did.
I purchased a 15metre usb extension lead. I spliced into the usb cable and cut the black and red power cables at each end near the plugs leaving about 10cms of red/black at one end still connected to the usb socket. Using a tobacco tin I soldered in a 5V positive regulator to the tin and added 1n, 10n, 100n, disc capacitors across the input leg to the tin and the 5v output leg to the tin. I also added 4700uf elec capacitors to the same pins. I slid ferrite beads over the red/black wires to the usb socket and soldered the black wire to the tin and the red wire to the 5v output. Using clip on ferrite beads i put over the usb cable as close to the socket as possible. I then used a small 12v battery to power the 5v regulator which is now interferance free (i will soon upgrade to a toridiol power supply). The RTL SDR is mounted inside a screened tobacco case with its own Power source. I also used clip on ferrite beads at intervals up the 15metres of usb extension. Ive now got the RTL SDR mounted up at the base of my antenna and well away from the computer. Its the switched mode power supplies in the computers that wipe out half of the band, they cause so much interferance.
The advantage of this is also that im using minimum coax between receiver and aerial as its mounted on the base of the pole, a lot less loss of signal. I grab some pictures soon of how to do this.

Happy scanning
barrylewis1234
 
Posts: 14
Joined: Mon May 21, 2018 10:53 pm

Re: Air band J Pole Antenna, Bargain - RTL SDR Noise fixe

Postby barrylewis1234 » Sun May 27, 2018 9:58 am

Ive just noticed that ebay shop has a J Pole on auction at only £19... Im going to bid on this and will post up my review of it if i win,
https://www.ebay.co.uk/itm/AirBand-Scan ... 2663767121
barrylewis1234
 
Posts: 14
Joined: Mon May 21, 2018 10:53 pm


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