Zaon MRX causing radio interference

With my new Zaon MRX PCAS mounted on top of my glare shield, I've been
experiencing some radio interference and linked this to the MRX: the
radio gives white-noise static -- like the squelch is not properly
adusted. When I turn the MRX off it goes away.

I've heard putting a "ferrite core" around the MRX's (and the
radio's?) power cord might help. (Here's one:
http://cgi.ebay.ca/Noise-Filter-Clip...QQcmdZViewItem
).

Does anybody else have this problem? Have you solved it in some way?

Thanks,

Eric
DG-300

JJ Sinclair reported an MRX/radio interference problem several years
ago on this forum. When I installed my MRX in my panel I took the
precaution of installing a ferrite bead around the power cable, and
I've had no interference problems. It's good electrical practice to
use ferrite beads on DC supply leads. If you can, loop the power cable
so it goes through the ferrite core more than once in order to get the
best high frequency attenuation.

-John

On Mar 24, 1:58 am, wrote:
With my new Zaon MRX PCAS mounted on top of my glare shield, I've been
experiencing some radio interference and linked this to the MRX: the
radio gives white-noise static -- like the squelch is not properly
adusted. When I turn the MRX off it goes away.

I've heard putting a "ferrite core" around the MRX's (and the
radio's?) power cord might help. (Here's one:http://cgi.ebay.ca/Noise-Filter-Clip...QQitemZ3501565...
).

Does anybody else have this problem? Have you solved it in some way?

Thanks,

Eric
DG-300

On Mar 24, 2:58*am, wrote:
With my new Zaon MRX PCAS mounted on top of my glare shield, I've been
I have the same problem. I also had the problem with the previous
model. I did the ferrite bead and it didn't do the job.
I finally sent it in and they replaced the power mosfet and that did
the trick.
I'm about to send this one in for a firmware upgrade and to deal with
this issue. Hopefully the same way.

Cheers,
Tim
1FL

experiencing some radio interference and linked this to the MRX: the
radio gives white-noise static -- like the squelch is not properly
adusted. When I turn the MRX off it goes away.

I've heard putting a "ferrite core" around the MRX's (and the
radio's?) power cord might help. *(Here's one:http://cgi.ebay.ca/Noise-Filter-Clip...QQitemZ3501565...
).

Does anybody else have this problem? *Have you solved it in some way?

Thanks,

Eric
DG-300

On Mar 24, 6:01*am, qflyer1 wrote:
On Mar 24, 2:58*am, wrote: With my new Zaon MRX PCAS mounted on top of my glare shield, I've been

I have the same problem. I also had the problem with the previous
model. I did the ferrite bead and it didn't do the job.
I finally sent it in and they replaced the power mosfet and that did
the trick.
I'm about to send this one in for a firmware upgrade and to deal with
this issue. Hopefully the same way.

Cheers,
Tim
1FL

experiencing some radio interference and linked this to the MRX: the
radio gives white-noise static -- like the squelch is not properly
adusted. When I turn the MRX off it goes away.

I've heard putting a "ferrite core" around the MRX's (and the
radio's?) power cord might help. *(Here's one:http://cgi.ebay.ca/Noise-Filter-Clip...QQitemZ3501565...
).

Does anybody else have this problem? *Have you solved it in some way?

Thanks,

Eric
DG-300



Make sure you are installing a large enough ferrite bead (beads is
slang, fat walled cylinders might be a better description) that allows
the power cable to go through the middle and be wrapped around the
outside several times. Use a thin gauge wire cable to help with this
and the bead can still be small and allow you to feed the cable
through several times. It may be worth trying to installing this close
to the Zaon end of the power cable if it does not work elsewhere.

Darryl

Here is a reply I sent to JJ's note on March 9 2007. As an added bonus
a question (good for EE job interview): Why does wrapping DC power
cord around ferrite core work to suppress noise? The supply and return
currents should cancel itself.

John's choke is a real overkill, but it is "guarranteed to work".
Coils are JW Miller & Bourns FB20010-3B-RC (DigiKey M8694-ND - may be
different now) cost
about 70-85 cents each depending how many you buy. Capacitor is a
standard ceramic 0.47 microFarad. I may have used 1 uF. I do not have
part number, but there is nothing particularly special about it (just
do not get one rated for 1kV ).

----WWWW-----WWWW----
I
-----
-----
I
----WWWW-----WWWW----


Best I can do for schematic is above. Put it as close to the noise
generator as possible.


Cheers,


Henryk Birecki




On Mon, 23 Mar 2009 23:58:25 -0700 (PDT), you wrote:

With my new Zaon MRX PCAS mounted on top of my glare shield, I've been
experiencing some radio interference and linked this to the MRX: the
radio gives white-noise static -- like the squelch is not properly
adusted. When I turn the MRX off it goes away.

I've heard putting a "ferrite core" around the MRX's (and the
radio's?) power cord might help. (Here's one:
http://cgi.ebay.ca/Noise-Filter-Clip...QQcmdZViewItem
).

Does anybody else have this problem? Have you solved it in some way?

Thanks,

Eric
DG-300

wrote:

With my new Zaon MRX PCAS mounted on top of my glare shield, I've been
experiencing some radio interference and linked this to the MRX: the
radio gives white-noise static -- like the squelch is not properly
adusted. When I turn the MRX off it goes away.

I've heard putting a "ferrite core" around the MRX's (and the
radio's?) power cord might help. (Here's one:
http://cgi.ebay.ca/Noise-Filter-Clip...QQcmdZViewItem
).

Does anybody else have this problem? Have you solved it in some way?

Thanks,

Eric
DG-300

On Mar 24, 9:31*am, Henryk Birecki wrote:
Here is a reply I sent to JJ's note on March 9 2007. As an added bonus
a question (good for EE job interview): Why does wrapping DC power
cord around ferrite core work to suppress noise? The supply and return
currents should cancel itself.
[snip]

Henryk Birecki


Not sure I'd pass an EE job interview, but inductive coupling of the
switched current can produce in-phase noise on both input leads. The
power supply circuit inside the Zaon may have issue with how it
handles RF grounding that makes this more likely.

At least in my case wrapping both leads a few times though the ferrite
choke worked. If it does not then slitting each lead and doing this
separately should fix things. Failing that use a full on filter like
Henryk describes.

BTW a nice power supply cable for the Zaon is aviable from Digikey see

http://www.digikey.com/scripts/dksea...196-ND&x=0&y=0

Darryl

Tim, that's very interesting. I have a friend who bought a MRX last
summer. While flying with him last fall I noticed that his MRX was
misreading the altitude of the tow plane. He's planning on sending it
in, but what with his problem and now yours I wonder if there was a QC
problem at Zaon last year. Don't get me wrong, I love my unit and I
know several that are performing exactly as they should - but they're
all older units.

-John

On Mar 24, 8:01 am, qflyer1 wrote:
I have the same problem. I also had the problem with the previous
model. I did the ferrite bead and it didn't do the job.
I finally sent it in and they replaced the power mosfet and that did
the trick.
I'm about to send this one in for a firmware upgrade and to deal with
this issue. Hopefully the same way.

On Mar 24, 12:57*pm, jcarlyle wrote:
Tim, that's very interesting. I have a friend who bought a MRX last
summer. While flying with him last fall I noticed that his MRX was
misreading the altitude of the tow plane. He's planning on sending it
in, but what with his problem and now yours I wonder if there was a QC
problem at Zaon last year. Don't get me wrong, I love my unit and I
know several that are performing exactly as they should - but they're
all older units.

-John
[snip]


By how much? And just compared to the towplane? The altitude of the
towplane sent to the Zaon is digital. So it is unlikely to "misread"
it. It uses it's own internal altimeter to calculate the relative
altitude. I would hope they agree to 100' or so. One issue is the Zaon
pressure sensor is exposed to ambient cockpit pressure and not the
static line pressure, so opening and closing vents/speeding up etc.
might affect the relative altitude it displays. If the difference is
more than a few hundred feet I'd next suspect the pressure sensor in
the Zaon.

It may be worthwhile before sending the Zaon back to compare what the
Zaon says to another aircraft that has a transponder that shows the
encoder's pressure altitude and play with opening and closing vents.
Of course if it is just the tow plane then it's encoder may also be
faulty, or maybe it really is an RF related problem that only happens
when close to the other transponder (but unlikely).

Darryl

It was 300-400 feet off, sometimes above and sometimes below us - and
we were doing a normal tow, not boxing the wake. Vents were closed (it
was 35 degrees F on the ground before takeoff). Hopefully he and I
will be able to fly together within the next month. I've got a Becker
ATC4401 that reports the encoded altitude, so we'll be able to compare
that with his MRX in real time at different separation distances and
heights.

-John

On Mar 24, 3:11 pm, Darryl Ramm wrote:
By how much? And just compared to the towplane? The altitude of the
towplane sent to the Zaon is digital. So it is unlikely to "misread"
it. It uses it's own internal altimeter to calculate the relative
altitude. I would hope they agree to 100' or so. One issue is the Zaon
pressure sensor is exposed to ambient cockpit pressure and not the
static line pressure, so opening and closing vents/speeding up etc.
might affect the relative altitude it displays. If the difference is
more than a few hundred feet I'd next suspect the pressure sensor in
the Zaon.

It may be worthwhile before sending the Zaon back to compare what the
Zaon says to another aircraft that has a transponder that shows the
encoder's pressure altitude and play with opening and closing vents.
Of course if it is just the tow plane then it's encoder may also be
faulty, or maybe it really is an RF related problem that only happens
when close to the other transponder (but unlikely).

Darryl

On Mar 24, 10:30*am, Darryl Ramm wrote:
On Mar 24, 6:01*am, qflyer1 wrote:



On Mar 24, 2:58*am, wrote: With my new Zaon MRX PCAS mounted on top of my glare shield, I've been

I have the same problem. I also had the problem with the previous
model. I did the ferrite bead and it didn't do the job.
I finally sent it in and they replaced the power mosfet and that did
the trick.
I'm about to send this one in for a firmware upgrade and to deal with
this issue. Hopefully the same way.

Cheers,
Tim
1FL

experiencing some radio interference and linked this to the MRX: the
radio gives white-noise static -- like the squelch is not properly
adusted. When I turn the MRX off it goes away.

I've heard putting a "ferrite core" around the MRX's (and the
radio's?) power cord might help. *(Here's one:http://cgi.ebay.ca/Noise-Filter-Clip...QQitemZ3501565...
On the previous model I did wrap several turns on the bead. Only
sending it in fixed the problem.
On this one, I'm not wasting my time. I'm awaiting my rma # as I
write.
Seems to me whatever power supply, or downstream component, design
they used before is the same now.

Tim


).

Does anybody else have this problem? *Have you solved it in some way?


Make sure you are installing a large enough ferrite bead (beads is
slang, fat walled cylinders might be a better description) that allows
the power cable to go through the middle and be wrapped around the
outside several times. Use a thin gauge wire cable to help with this
and the bead can still be small and allow you to feed the cable
through several times. It may be worth trying to installing this close
to the Zaon end of the power cable if it does not work elsewhere.

Darryl