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Gemobis1

Goof proof patch for foreigners

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Hello everybody from a new member

I am about to start the building of the GP patch but many measurements are given in US system and though it's probably not so important, what is the thickness in mm of the metal from which I'll cut out the radiator and reflector? (24to 30 gauge sheet)? What is the diameter of the added short piece soldered to the centre post(24-26 AWG)?

Before soldering this extra bit to the small metal plate would it be possible to maintain it with a short piece of shrinkable tube which will stay there of course?

If I have understood properly the wooden spacers should be 0.20*0.20*0.25 in mm 5*5*6 . It does make a slight difference.

To finish with my questions should the patch stay naked or is it possible to wrap it in Oracover or paint it? Does it change anything in its performance if the patch touches the box where the receiver is, which might be a metal box? Thankings to any one who will take the trouble of answering my questions and good flights to all. Gemobis1

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Take a look around the forum; Your GP Patch questions have been discussed before, so you should be able to find good information in the past discussions.

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Hello Mr RC-CAM Thank you for answering my post. Looking through the 3 pages about the GP Patch I found a few answers to my questions, particularly the wrapping with Oracover or similar, although I can't see why wrapping the outside without changing anything between the two plates should affect the signal. I 'll abstain from holding the piece of wire to the the centre pin of the SMA plug with a piece of heatshrink while soldering, I'll hold it with something I can remove afterwards. I've had to order this SMA Plug to Conrad in Germany, the male inverted type for PCB is not to be found round Toulouse where I live. My only problem is that their data mention an impedance of 80 ohms instead of 50, which I find hard to believe. The plates could be from 0.4 to O.7 mm thick, the small holes 1.5 mm and the big ones 2.5mm and for the soldered centre bit 0.4 to 0.5 mm should be suitable. Thank you for your work, I'won't forget to report about the results obtained with my antenna.

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I can't see why wrapping the outside without changing anything between the two plates should affect the signal.

The signal travels over the surface of the whole aerial and the effect of covering any of it can not be forseen.

My only problem is that their data mention an impedance of 80 ohms instead of 50, which I find hard to believe

80 ohms is close enough to make no noticable difference.

The exact thickness dose not matter so much, the design seems to work well even when built with different thickness plates or connectors but the closer to the design the better.

If you stick to the exact design the performance is know but if you change things it will still work but the performance will not be known.

Terry

Edited by Terry

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