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Scooby

Advice reqd - Coax Shield

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Hi guys,

I'm playing around with a UK 1.2GHz Tx (12v) and experimenting with antennas to optimize range and reduce video drop-out. The TX comes from a local manufacturer in the UK and is suplied with a rubber duck style antenna which is now in the trash can. There is no metal case to the TX unit, instead it is wrapped in heat shrink rubber. Looking at the circuit board I can clearly identify the Antenna signal contact, but what should I connect the coax shield to? I seem to remember reading somewhere that connecting it dirctly to the 12v neg track is going to reduce the antenna effectiveness.

Thanks for any advice

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what should I connect the coax shield to?

Connect it to any substantial "RF ground" PC trace that is at the RF output. The goal is to keep the exposed shield and signal wires lengths to a minimum (anything over .1" may begin to impact performance). The place you solder the shield must have lots of copper area in order for it to act like as a good RF ground.

Also, the length of your coax can matter too. Keep it short and if necessary trim its length (via emperical testing) to minimize SWVR issues.

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Thanks Mr RC_Cam, I'll give that a try.

I've calculated all the coax feedlength and antenna element sizes using the information on these forum pages, so I'm hoping for some excellent results.

Thanks to all

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