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Reduce the RF interference at voltage regulator



Jan 1, 1970
I have a voltage regulator circuit. A two way radio is operating near
the circuit. When I probe the output voltage of the regulator, it
seems like the voltage fluctuated in a great amplitude when the radio
is transmitting. The RF inteference cause the voltage to go up and
down. What can I do to reduce the voltage fluctuation? Is it advisable
to put a few bypass capacitors at the voltage regulator input and
output to bypass the RF frequency from 200-800MHz? Or something like
putting a RF shield around the regulator?

The capacitors should be chosen in such a way the they would cover the
frequency bands stated above. What I am worrying is that the capacitor
will load down the voltage regulator and causing output voltage to be
slowed down. Any concern on the ESR of the capacitors as well? Please

tempus fugit

Jan 1, 1970
If you haven't got any bypass caps at the in and out of the regulator, then
yes, the first thing I would do is out some in. Try anywhere from 10 - 100
uF paralleled with a .1 or.01 uF at both in and out. The bigger cap may not
be necessary at the output, but I would put the smaller ones at both.

Is the regulator in a separate enclosure from the radio circuit? If it is,
put it in a metal box.