Beer-CanTenna – A ground antenna for 433MHz TX

This antenna was posted in 2012 on FPVLAB, obviously never made it into the blog…solved. 😉

Just in case someone needs a simple and easy to build ground station antenna, usable with any 433MHz TX, here is a solution:

Beer-CanTenna measurement setup:
Return loss at 433MHz:
Inside the can:
On a tripod, extended to ~3m height:

What you need:
1x Beer can, height 170mm, outer diameter 66mm, top opening diameter 52mm
1x Steel welding rod, 500mm length, diameter 1.5mm
1x BNC or SMA panel mount socket with front side nut

How to build:
– First, enjoy the beer, thats a mandatory step. 😉
– Remove the top cover of the can. In a way, that you keep the outer folded ring.
-Drill a hole in the bottom center to insert the BNC/SMA socket.
– Solder the welding rod to the BNC/SMA center contact.
– Measure the length of the rod including the center contact and cut the overall length to 490mm.
– Insert the socket through the bottom hole and fix with the nut.
– Cover the top opening with some non-conductive material. I used some EPS foam.
– That’s all.

I made a extension pipe with a BNC socket on one end and some tripod adapter on the other. This way I can raise the antenna up to 3m on the tripod.
Extention Ext_Socket Ext_Cable
The antenna connects with a 5m BNC cable to the transmitter.

I have tested the antenna during my 11km flight with excellent results.

A fellow pilot uses a second antenna with 433MHz 3DR radio modes to control his APM2.5 plane. He was 3km out already then chickened.

Note, a different size beer can may require a different length of the welding rod.

Improving a ReadyMadeRC RMRC-700VXP camera

I got two ReadyMadeRC RMRC-700VXP cameras from a clearance sale with 50% off. The cameras were announced to have issues while running at 5V and causing sync problems when the supply voltage just dropped to 4.95V or below. Tested both and the issue was present.

Luckily, this issue can be easily fixed by replacing a chip ferrit bead on the cameras board. Obviously the manufacturer chooses one with unsuitable high DC resistance that causes a significant voltage drop when the camera is operated at 5V. I replaced the ferrit bead by different one, known to have a low DC resistance. Now both cameras running fine down to 4.6V.

Well, two cameras for the price of one + 30min additional work = nice deal. 😎 By the way, these cameras are one of the best you can get. Have them already running on my Skywalker and Fascination.

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