How to make a simple half-wave dipole useful for 433MHz LRS.

You need:

  • SMA Pigtail with your desired coax length, the cable I used is RG316
  • Plastic antenna tube (found some made by Reely here in Germany, 380mm long)
  • Two pieces of wire each 200mm long, I used AWG28
  • Hotglue

Required parts

Mark the center on the antenna tube and use a solder iron to make a small hole in the tube right at the center. Do not cut the tube in half, this will give a better mechanical stability.
Prepare the open end of the SMA pigtail. Keep the feedpoint cap as short as possible.

Prepare open end and antenna tube

Solder the two pieces of wire to the coax open end. Be sure the center wire will not touch the outer shielding.

Soldered wires

Pull the wires through the antenna tube and the coax open end into the tube hole.
Then apply some good amount of hotglue to strengthen this point.

Dipole feedpointDipoleFeedpoint fix

Cut the antenna tube including the wires inside to an overall length of 300mm. Each half of the tube to 150mm.

Overall length 300mmEach half 150mmReturn loss

On my EZ* I sticked the dipole through the wing. On the lower end, the antenna tube (and only the tube!) was cut and put back together using silicon fuel tube (from nitro engines). This way it’s flexible and will not break in case of ground contact during landing.

Dipole on Easystar wing

 

You know where to go for FPV:

FPVLAB

 

Awesome talk, a must see:

Find more: http://www.youtube.com/user/28c3

 

Got a GPS-GSM tracker today which I ordered some days ago at eBay.
http://www.ebay.com/itm/320762016759

I plan to use the tracker in my biggest FPV plane for location in case of a long range crash.

The housing is a way bulky and heavy even for a big plane. So could not resist to disassemble the tracker to check if size and weight can be reduced.

Here is the outcome:

Some notes about the hardware:

  • SiRf Star III GPS chipset, stand alone module, soldered to the main PCB
  • GPS antenna is detachable, fixed by two solder blobs
  • plug-on GSM module
  • GSM antenna seems to be crap, but there is a U.FL socket on the GSM module to connect a better antenna
  • 8-pin USB Connector, at least the USB logo is on the charger plug
  • Microcontroller STC 89LE58RD
  • there is a microphone
  • Weight of empty housing: 22.2g
  • Weight of PCB including GSM modem: 21.6g
  • Weight of battery: 18.3g

[Update]

I have added a picture which show two pads for the microcontrollers serial interface.
Parameters are 19200 Baud 8N1. After power up (without SIM card) there is a loop transmission of AT+CREG.

 

For testing purpose I ordered a OSRAM SFH4236 IR LED.  I did some test in my backyard to see how it performs.

Setup:
600TVL Camera with Hitachi chipset http://www.securitycamera2000.com/products/Hitachi-DSP-Wide-Dynamic-Frame-Integral-Sony-CCD-4mm-Board-Camera.html
IR filter removed on the cameras sensor!

4mm IR Lens http://www.securitycamera2000.com/products/1%7B47%7D3-4mm-MTV-Mega-Pixel-Infrared-Sensor-Lens-F1.2-for-CCTV-Camera.html

SFH4236 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=475-2911-1-ND

Ledwarrior01 current source to power the LED @ 1.36V/700mA

Results:
Of course radiation is invisible to human eyes, so one must be very careful while operating the LED!

The above video was taken while operating the plain LED.

Exchanged the white LED on a starboard with the IR LED. The starboard is equiped with a 10° optical lense:

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