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Old 02 July 2016, 11:27   #1
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RF Noise new VHF setup

Hi all

I posted this to the inflatable boat section

new vhf setup

Made a waterproof enclosure for my VHF. Inside is a gel battery and a 12v to 5v step down transformer to power the 5v GPS mouse and also give a USB charge point on the box.

However, I'm getting some interference. What I receive and what I transmit is being muted for a split second at a regular interval of approx. 2 seconds. Someone on this forum suggested the fault might lie with the 12v to 5v 'buck' converter that powers the GPS, so I disconnected it and connected the GPS to a 5v battery source instead. The interference has gone. So I'm looking for a 12v to 5v step down that won't introduce this interference. Any ideas? Apparently virtually all 'buck' converters are notorious for noise.

Many thanks

Simon
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Old 02 July 2016, 13:32   #2
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Can you use a soldering iron? It's very simple to make a 1.5amp regulator, only three components are required. Just google 7805 regulator circuit and you'll find umpteen pictures of a suitable circuit.

Personally, I'd use a 0.47uF capacitor on the input and both a 0.1uF and a 10uF capacitor on the output side to suppress any noise and smooth the output. The tab is ground and needs to be heat sunk - bolt it to your radio box. The other components are so small you could possibly solder them directly to the 7805 legs so prevent having to make a circuit board but if you have a bit of vero board, so much the better.
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Old 02 July 2016, 14:02   #3
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Quote:
Originally Posted by jwalker View Post
Can you use a soldering iron? It's very simple to make a 1.5amp regulator, only three components are required. Just google 7805 regulator circuit and you'll find umpteen pictures of a suitable circuit.

Personally, I'd use a 0.47uF capacitor on the input and both a 0.1uF and a 10uF capacitor on the output side to suppress any noise and smooth the output. The tab is ground and needs to be heat sunk - bolt it to your radio box. The other components are so small you could possibly solder them directly to the 7805 legs so prevent having to make a circuit board but if you have a bit of vero board, so much the better.
Thanks, very useful. Yes, I am handy with a soldering iron. I'll have a look, cheers
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