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RF problem caused display to blank

I have one radio (330Mhz-400MHz), equipped with antenna and remote speaker mic. When the radio is transmitting at 4W over a groundplane with LCD display facing down, display blank problem could be seen occasionally. The display was totally blank and not functioning. Of course, radio was still working well. Turning the radio OFF and ON again would have the display recovered.

A copper tape that applied at the LCD flex solved the problem. But no display blank issue was not seen at other bands of radios such as from

100MHz-200MHz and 400MHz-500MHz. All radios are using same LCD, same circuitry and similar platform design. Even though the problem has been solved, the behaviour of the display blank problem was not properly understood, especially when it's frequency dependent, and it happened when display was facing downwards the big groundplane, and it didn't happen at other bands of radio. Can somebody shed some light on this?
Reply to
Dummy
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One or more of the connections to the LCD was probably acting as an antenna at that particular frequency or a harmonic of it.

Leon

Reply to
Leon Heller

I read in sci.electronics.design that Dummy wrote (in ) about 'RF problem caused display to blank', on Wed, 9 Mar 2005:

Typical EMC mystery problem. Of course it can be explained. Start with Maxwell's Equations and go on from there. (;-)

Alternatively, just remember that things like that can happen.

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Regards, John Woodgate, OOO - Own Opinions Only. 
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Reply to
John Woodgate

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