https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/ Guitar Noise Discussion Board en-US Thu, 04 Jun 2026 08:34:59 +0000 wpForo 60 https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54880 Fri, 26 Sep 2003 23:27:01 +0000 a little background in radio, i'll give you some of
what i have done to solve BCI ( Broadcast interference)
problems.

One thing to remember also is that Radio Signals
are just high frequency AC currents, which have
somehow induced themselves into your circuitry,
and is being decoded by the semiconductor devices
in your equipment ( i.e., diodes, which any transistor
or FET can behave like . . . even corrosion on a
phono jack can turn your PA into a marvellous
crystal set in the presence of hi energy RF.)

One way to get BCI/ RFI ( Radio Frequency
Interference ) out of a system is to kill accidental
detectors that may have formed along the runs
of your system.

Inspect each input to your mixer and amps, and
be sure the plugs are clean, too.  Even a little
corrosion equals a semiconductor.  Inspect the
shields on the long runs, the snake, etc.  Cables
are notorious for distributed capacitances which
are capable of literally tuning long runs to RF.

If you see corroded switches or sockets, use
a little "DeOxit" or similar cleaner, Radio Shack
has TV Tuner cleaner which will work in a pinch
for copper oxides.

Another way of killing the RF gremlin is to short
the sucker out.

A good way to short out RFI/ BCI.energy is by
using a capacitor, somewhere between 100pF to
.01uF, value is not all that critical, and shunt cable
inputs and outputs to ground.  Try shunting the
center conductor of your shielded wire to the
shield, if the manufacture has not already done
that. These caps are known as RF bypasses.
They will pass a.c., but block d.c. The ultimate
high pass filter, if one views d.c. as the ultimate
low frequency.  These will have no effect on your
input/ output impedances.

Get help from the RFI Gremlin Maker.
Which means you have to identify the RFI source.

If you are in a densely RF saturated area, called the
"field" of a commercal broadcaster, you might enlist
the help of one of the station engineers.  BCI filtering
may be involved.  Back in the tube era, we used
to shunt the filaments to ground, and balance
shunt the power input to the primary transformers.
RF ( Radio Frequency energy ) can get in via the
power mains.  Also, if it is a commercial or other
broadcaster, they might want to know.  They may
be in violation.  Part 15 FCC rules and regs cover
low power devices, and owners of equipment are
seen by law to have to put up with a certain amount
of interference, but if all else fails, the FCC often takes
a dim view of RF saturation.  Especially if it is the
result of a transmitter running out of spec.  Very
costly to the station.  Even ham radio stations
are required to meet a certain standard, although
sometimes RFI is impossible to completely cure
at the station end.  FCC and Part 15 recognises
that, too.

Proper Grounding

Grounding your system to planet earth is only
good if the house is grounded to planet earth.
Some cases have differences of several, even
nearly a hundred volts difference between house
"ground" and true earth.  But still, shunting
to "chassis" ground can make the system look
like a short to RF.  Also, make sure that if your
system has several perpherals, that there is a
common ground tie source, to avoid ground
loops ( probably described in your mixer manuals.).

Ground loops can become an efficient antenna.
( I know, because in short wave work, we used to
tune our grounds! )

Get help from equipment manufactures.

I had restored recently an old Peavy MK-II eight
channel for use with my ADAT, and was in phone
contact with Peavy techs, who were extremely
helpful.  All this to say, contact the manufacture
if you have a stubborn situation, they might have
advice to help.

Just to insure you are not detecting out of band
signals with any wireless equipment you might
have in line, unplug them, and run the system
without them.  See if the gremlin rears it's ugly
head.  Provided everything else checks out fine,
and the RFI only happens when the wireless
equipment is installed, you have an equipment
issue, bad bandpass filtering of the receiver.
OR crossmodulation, a result of the superheterodyne
mixing process which makes an interfering signal
appear at the output of a radio receiver. Both are
equipment issues only the manufacture can solve,
unless you are a homebrew-type.

Well, i'll move along, but i hope this might help
you with some avenues to pursue, and Good
Providence in all your endeavours!

-gary // wd4nka ( designer of Regenerodyne
sw. receivers. Very lo teck.)

http://www.qsl.net/wd4nka/]]> Live Sound Anonymous https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54880 https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54879 Wed, 03 Sep 2003 18:39:52 +0000
If the snake consists of a number of separate cables, try twist them around each other in a long spiral. You can try simply tying a knot in the snake close to the PA. That may be all you need to stop the bleed.

]]> Live Sound greybeard https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54879 https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54878 Tue, 02 Sep 2003 19:24:14 +0000                   I appreciate the suggestions and have followed your instructions to the letter.  But I still have bleed over.  Disconnecting the wireless Mics and Laveliers didn't fix it.  So I'm thinking that I may need to move the snake to another location.  Like?  :'( :'( :'(But I'm investigating if there is a way to run it under our area versus up in the church attic.  But all suggestions area still welcome.

Nelson]]> Live Sound Anonymous https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54878 https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54877 Fri, 29 Aug 2003 09:57:07 +0000
Some FM wireless have this problem of picking up stations. Change the frequency.

Just a thought.

joe]]> Live Sound forrok_star https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54877 https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54876 Thu, 28 Aug 2003 22:18:23 +0000
Anyway, check the grounding and shielding of everything!  Read this for some clues:
https://www.guitarnoise.com/sound/20000509.php

You've guessed that it's the snake.  So the radio goes away when the input faders are down, and the master faders are up - correct?  Does your mixer have a headphone output?  Can you hear the radio in the headphones with the faders up and the amps turned off?  Do you hear the radio when ou play a CD through the system?

Let me know if these questions and suggestions help.

-Laz


]]> Live Sound Dan Lasley https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-54876 https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-1283 Thu, 28 Aug 2003 20:18:12 +0000
Please Help,
Needed Badly,
Needed Yesterday,

Nelson]]> Live Sound Anonymous https://guitarnoise.forum/live-sound/radio-station-bleed-over-into-a-church-pa-system/#post-1283