Zaon MRX causing radio interference 2

"qflyer1" wrote in message
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On Jul 23, 12:50 am, "Tim Ward" wrote:
"Itsaplane" wrote in message

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I'm starting a new thread on this topic as the old one sort of drifted
off-topic and its conclusions don't seem to reflect what I've found...

I have a Zaon MRX which is *using external ship's power* which is
causing radio interference. I know it's the Zaon because when the
radio goes to static, in flight, as if the squelch wasn't adjusted,
turning off the Zaon immediately stops the problem.

Following the recommendations of this forum, I've installed one, then
two, then three ferrite cores on the Zaon end of the power cord. Each
additional core has reduced the number of static problems I've had,
but not to zero (and not to where I don't have to frequently turn the
damned thing off!).

Calling Zaon tech support today (800-496-9430 x-311/312), they say
they have a particular problem with sailplanes -- something about our
radios being particulary sensitive because they're low power compared
to a larger, standard GA unit on a power plane.

As such, they don't have any real solutions for running with external
power. He did suggest either a) trying more ferrite cores on the
Zaon power lead (!), b) trying a ferrite core on the negative (?) side
of the radio's power lead, or for the sure fix c) running the Zaon off
its internal battery or a *separate* external battery other than the
one driving the radio.

Anybody have any other suggestions?

Eric

Has anyone tried a cap across the power leads right at the Zaon's case?
I don't know what the connectors are like, so I don't know how close you
can
go.
Inside the power connector would be ideal.
But a 25 volt or higher .01 uF in parallel with a .001 uF might help, and
shouldn't hurt anything at DC.

Tim Ward

Tim, are you recommending a polarized .01 and a ceramic .001?
I, too, have the dreaded ZAON issues.


Thanks,
Tim Larsen


Actually, I was thinking of a couple of ceramic surface mount chip caps
inside the power connector.
But having looked at the Zaon input power specs of 40 Vdc, I might go for 50
V caps.
However, since this is connected to wiring that doesn't have an alternator
to drive the voltage up and put spikes on it, you could make the case that
16 wvdc would be okay.

I don't own a Zaon, have never attempted this, attempt at your own risk,
etc.

But in theory, it shouldn't hurt anything.
Tim Ward

This afternoon I found when I connected my brand new Zaon to ship's
power that I had Zaon squelch disease. I ran the factory supplied Zaon
power lead through a 1" long by 1/2" diameter non-split ferrite three
times right next to the power plug, then connected to power and ground
behind the instrument panel. For what it's worth, I hear noise on
123.00 but not on 123.30, while on the ground. In flight all
frequencies were quiet when I was using the internal Zaon batteries.

Tomorrow I'll buy another power tip, and connect it to a shielded two
conductor cable temporarily running directly to the ship's battery. If
that doesn't work, I'll try a 25 V polarized 0.01 uF capacitor in
parallel with a ceramic 0.001 uF capacitor near the power tip, if
Radio Shack has them in stock. If I can find another ferrite I'll put
one on power and one on ground, too.

Wierd - my old Zaon (bought August 2006) never exhibited this problem
in my ASW-19, and it was wired exactly as I wired the new Zaon in my
LS8 today. Similar age Becker AR4201 radios in both the -19 and the
LS8, but maybe there's a different squelch level adjustment and/or
changes to the new Zaon board.

I'll report on the results of my experiments - there may be a delay,
as the temps tomorrow are going to be God awful...

-John

Can someone post a link to the original thread on this topic? Google
Groups has "improved" their search engine, and I cannot locate the
original thread and/or related threads. I also tried Glider Pilot
Network, but there's no search available on that site.

-John

I did a set of noise experiments using my Zaon MRX and my Icon A6.

The setup for the Zaon was (1) Flight Mode = On, (2) Brt down until
just disappears, (3) Antenna pointed vertically, (4) Power – internal,
external, external w/ 0.01uF ceramic and 0.1uF metal film caps in
parallel across power leads at tip going into Zaon (I couldn’t fit my
1” long by 1/2" diameter non-split ferrite into the test rig).

The setup for the Icom was (1) Frequencies 123.300, 123.075, 122.800,
(2) Internal batteries, (3) Antenna pointed vertically (4) unit on
opposite site of power input to Zaon and external battery.

The testing procedure was (1) Place antennas 3 inches apart, (2)
Reduce squelch from highest value until sound appears, note number,
increase squelch, reduce squelch, note number, repeat until lowest
consistent squelch number is obtained.

Test 1 – Zaon on internal batteries, Test 2 – Zaon on external
battery, no caps, and Test 3 – Zaon on external battery, caps used.

Results:
Test 1 Test 2 Test 3
Internal External Ext w/ caps
123.300 5 18 14
123.075 5 24 21
123.800 5 24 16

It’s clear that the Zaon radiates noise when running on an external
battery. It’s also clear that the 0.01uF ceramic and 0.1uF metal film
caps in parallel across the Zaon power leads reduce the noise the Zaon
is radiating, but they are nowhere near as effective as running the
Zaon on internal batteries.

Any electrical engineers out there who'd like to make some suggestions
for further tests to help me try and get the Zaon noise down?

-John