Zaon MRX causing radio interference 2

[Itsaplane[_2_]]

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

[Matt[_2_]]

Eric,

We have installed our MRX in the panel, and so far without issues. I
put one large dia (non split) ferrite on the power line to to MRX.
Ferrites are designed to work at a particular range of frequencies, so
you might look into that. Also, run the power line through the core
3-4 times. each time improves noise suppression. Don't use the clamp
on half shell type ferrites because if the two halves are not
contacting, the ferrite does not do it's job. Otherwise, turn the
squelch up! ;-)

Matt

[Bob]

I have the same problem. The Becker radio has a separate battery
though. I have not tried ferrite cores.

What I found was I could stop the problem by applying inward pressure
on the power cable, but once I released the pressure it was back to
unsquelched radio. It stops also if I move the unit further away from
the radio. I cannot figure out why the problem is intermittent. I
would think it would constantly cause interference, but it comes and
goes.

I'd be interested to know if yours stops with pressure applied to the
plug.

I have not tried adjusting radio squelch settings as the radio is at
the bottom of the stack and the adjuster is buried within. And I
cannot force the problem to happen on the ground.

Bob

[Eric Greenwell]

Itsaplane wrote:
> 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.

1) Does the static problem go away when you use it's internal battery?
If it doesn't, your problem isn't the power lead and could be a radio
wiring problem, or maybe an MRX defect.

2) Have you tried another MRX to see if it has the same problem? Try to
borrow the newest one you can find, as the older ones did not have as
much "rf emission control".

3) Run a new power lead to the MRX directly from the battery terminals,
using shielded, twisted pair cable. Connect the shield to the negative
(-) terminal on the battery, along with the negative lead. Don't connect
the shield to anything at the MRX end. I believe this cable from Radio
Shack will work:

$9.89

50-Ft. Audio Cable - RadioShack.com
50-Ft. Audio Cable
Model: CL2 UL Approved | Catalog #: 278-513

Do the simplest - but still safe - installation to test the idea. You
can do permanent installation it works, including fusing the lead at the
battery.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[Rick Culbertson]

On Jul 22, 2:32*pm, Eric Greenwell > wrote:
> Itsaplane wrote:
>
> * > 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.
>
> 1) Does the static problem go away when you use it's internal battery?
> If it doesn't, your problem isn't the power lead and could be a radio
> wiring problem, or maybe an MRX defect.
>
> 2) Have you tried another MRX to see if it has the same problem? Try to
> borrow the newest one you can find, as the older ones did not have as
> much "rf emission control".
>
> 3) Run a new power lead to the MRX directly from the battery terminals,
> using shielded, twisted pair cable. Connect the shield to the negative
> (-) terminal on the battery, along with the negative lead. Don't connect
> the shield to anything at the MRX end. I believe this cable from Radio
> Shack will work:
>
> $9.89
>
> 50-Ft. Audio Cable - RadioShack.com
> * * * * * * * * 50-Ft. Audio Cable
> Model: CL2 UL Approved *| *Catalog #: 278-513
>
> Do the simplest - but still safe - installation to test the idea. You
> can do permanent installation it works, including fusing the lead at the
> battery.
>
> --
> Eric Greenwell - Washington State, USA
> * Change "netto" to "net" to email me directly
>
> * "Transponders in Sailplanes"http://tinyurl.com/y739x4
> * * * Sections on Mode S, TPAS, ADS-B, Flarm, more
>
> * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org


I too have the Radio/Mrx intermittent squelch problem, as do 3 or more
of my club members; all of us are using an external battery source,
not all of us have a transponder, so I don’t think the transponder is
the problem. In my particular case, I'm using a separate/ dedicated
battery with shielded cable to power the MRX & Transponder.

A few observations:
1) The separate battery for my Mrx is not fully isolated as Eric
suggested above, but it is fully shielded up to the Positive and
ground busses at the panel, and the Mrx unit has been serviced and
upgraded recently.
2) The squelch problem does not occur when the internal battery is
used on the Mrx.
3) I’ve noticed, for example, I can be on 123.3 when the squelch
interference occurs however if I quickly switch to 123.5 or any other
frequency no open squelch is detected. I can then go back on the
original 123.3 freq. and the squelch problem is still occurring. This
odd Mrx squelch interference behavior has also occurred on other
frequencies, a complete mystery to me.

Perhaps a full isolation of the Mrx external power system will be my
next step as I’ve nearly run out of ideas. We seem to have a deep pool
of smart minds here; perhaps someone will be able to take up the
challenge of this annoying mystery that Zaon has so far failed to do.

21

[Steve Koerner]

Rick:

There is nothing surprising about what you describe. That is how
harmonic interference is likely to play out. Let's say for instance
that the MRX has a 9.5 Mhz microprocessor clock; the 13th harmonic of
that would be 123.50 Mhz. But microprocessor oscillators don't need
to be perfectly precise. If yours happens to be low by 0.2% then
yours falls on 123.30 and someone else will find interference on
another nearby frequency or not at all if the 13th harmonic happens to
land right between radio channels or on a frequency that pilot B never
tunes in. I have an MRX with sloppy external power connections and
have never had interference; so maybe I am the pilot B case. Of
course, I don't really know what clock freqencies are actually used in
the MRX and I don't know which harmonic is the nasty in this case --
my numbers are just for illustration.

Bob:

The business of pushing on the connector is most likely that your
fingers are capacitively coupling into the spurious radio propogation
path between the MRX and radio. The propogation path is shunted or in
some manner altered enough to make a big difference in the
interference that you are hearing. I'll bet that if you just squeezed
the connector without pushing you would find the same effect.

Steve Koerner
(retired EE)

[Tim Ward[_1_]]

"Itsaplane" > wrote in message
...
> 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

[qflyer1]

On Jul 23, 12:50*am, "Tim Ward" > wrote:
> "Itsaplane" > wrote in message
>
> ...
>
>
>
> > 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

[Darryl Ramm]

On Jul 23, 4:06*pm, qflyer1 > wrote:
> On Jul 23, 12:50*am, "Tim Ward" > wrote:
>
>
>
> > "Itsaplane" > wrote in message
>
> ....
>
> > > 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

At RF frequencies you want a ceramic capacitor.

As has been suggested here before by others you may also want to split
the power leads and feed through separate ferrite chokes so you are
filtering differential mode noise as sell. Although feeding both
though a small ferrite choke solved my RF interference problems.

Darryl

[Tim Ward[_1_]]

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

[jcarlyle]

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

[jcarlyle]

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

[Itsaplane[_2_]]

On Jul 22, 1:32*pm, Eric Greenwell > wrote:
> Itsaplane wrote:
>
> * > 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.
>
> 1) Does the static problem go away when you use it's internal battery?
> If it doesn't, your problem isn't the power lead and could be a radio
> wiring problem, or maybe an MRX defect.
>
> 2) Have you tried another MRX to see if it has the same problem? Try to
> borrow the newest one you can find, as the older ones did not have as
> much "rf emission control".
>
> 3) Run a new power lead to the MRX directly from the battery terminals,
> using shielded, twisted pair cable. Connect the shield to the negative
> (-) terminal on the battery, along with the negative lead. Don't connect
> the shield to anything at the MRX end. I believe this cable from Radio
> Shack will work:
>
> $9.89
>
> 50-Ft. Audio Cable - RadioShack.com
> * * * * * * * * 50-Ft. Audio Cable
> Model: CL2 UL Approved *| *Catalog #: 278-513
>
> Do the simplest - but still safe - installation to test the idea. You
> can do permanent installation it works, including fusing the lead at the
> battery.
>
> --
> Eric Greenwell - Washington State, USA
> * Change "netto" to "net" to email me directly
>
> * "Transponders in Sailplanes"http://tinyurl.com/y739x4
> * * * Sections on Mode S, TPAS, ADS-B, Flarm, more
>
> * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org


I can confirm that the problem goes away when the Zaon is run on its
internal batteries (but I had to replace batteries twice in two 6+
hour flights). So the problem is with running the Zaon on external
power.

My next moves will be to follow suggetions I've received in this
discussion:

1) change the squelch setting on the radio (adustable if I pull out
this Dittel radio, I presume); if that doesn't work:
2) look for a non half-shell ferrite core; and if that doesn't work
3) replace the power cord with a shielded, twisted pair.

Oh, and is it fair to say that this is a KNOWN and WIDE-SPREAD
problem, at least for us poor glider pilot customers -- so it sure
would be nice if Zaon got its engineering team cracking on this
problem!

Eric

[jcarlyle]

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

[[email protected][_2_]]

Just a suggestion:

Get 4 good Nimh rechageable AA batteries and a good charger. Keep one
pair in the charger and other in the MRX. Switch after every flight -
or day, if several short flights.

Advantages: No radio noise, no extra wires, can use your MRX in other
gliders/towplanes.

Disadvantages: If you do a long out and back, may need to have some
backup AAs in your landout kit. Have to remember to charge and switch
batteries.

Works for me - the rechargeable batteries last long enough for a long
XC, and I like having my MRX in all the club gliders and towplanes I
often fly in.

Kirk
LS6 "66"

[jcarlyle]

Hi, Kirk,

That's a very sensible suggestion, but for various reasons too long to
go into now I want to put the MRX into my panel. So I must figure out
how to kill the radio noise caused by the Zaon when it's running on an
external battery.

-John

On Jul 29, 3:14 pm, " >
wrote:
> Just a suggestion:
>
> Get 4 good Nimh rechageable AA batteries and a good charger. Keep one
> pair in the charger and other in the MRX. Switch after every flight -
> or day, if several short flights.
>
> Advantages: No radio noise, no extra wires, can use your MRX in other
> gliders/towplanes.
>
> Disadvantages: If you do a long out and back, may need to have some
> backup AAs in your landout kit. Have to remember to charge and switch
> batteries.
>
> Works for me - the rechargeable batteries last long enough for a long
> XC, and I like having my MRX in all the club gliders and towplanes I
> often fly in.
>
> Kirk
> LS6 "66"

[Tim Ward[_1_]]

"jcarlyle" > wrote in message
...
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

Not an EE, but it might be interesting to see how a the length of the llne
to the battery affects things. I have a suspicion that the radiating
element is the power lead, rather than the antenna. They could be using a
switching regulator for external power (not unreasonable if you want a wide
input range and decent efficiency).

See if, with the Zaon antenna and power cord at right angles, rotating the
receiver antenna from parallel to the Zaon antenna to parallel to the
power cord makes the problem worse.
Sometimes it's useful to find how to make things worse, and that gives you a
clue as to how to make things better.

A different approach might be to supply your own regulator as a "battery
eliminator" that goes in place of the battery, supplying a filtered nominal
battery voltage.

But if a little is good, a lot may be better. Try paralleling a 10 uF cap
with what you have.
Keep increasing the capacitance until it doesn't help or gets worse.
Some linear regulators will oscillate with too little capacitance on the
input, but I would think Zaon would catch that.

Also, is the power cord through the ferrite as many times as it will fit?
The inductance is non-linear, it's proportional to the number of turns
squared. So managing another turn or two through the toroid may help.

Gosh, it's easy to come up with work I don't have to do myself.

Tim Ward

[jcarlyle]

Hi, Tim,

Thanks for your thoughts. While at the glider port yesterday I talked
with club member who’s a EE, and he seconds your suspicion that Zaon
is using a switcher. From their specs, it’s pretty inefficient (as
well as being noisy)! Your idea of replacing the batteries with an
efficient, RF quiet, 12VDC to 3VDC supply might be a good way to go
(although I don’t have the resources to do it).

I did a quick experiment and found that the RF noise is indeed coming
from the power lead, and it's polarized. The noise is less when the
VHF antenna is vertical when the power lead is in the horizontal
plane.

I found the original thread on this subject. In it, Henryk Birecki
posted a Zaon noise filter, made up of 4 Miller & Bourns FB20010-3B-RC
coils and 1 ceramic 0.47 uF capacitor. See
http://groups.google.com/group/rec.aviation.soaring/browse_thread/thread/311f150d7644c6df/650eafbb2ca4182c?

I found a 0.1 uF cap and some torroidal coils, Radio Shack 273-0108,
and built something similar to Henryk’s filter. It worked much better
than the 0.01uF ceramic and 0.1uF metal film caps I reported on
before:

Test 1 Test 2 Test 3 Test 4
Int Bat Ext 12V Ext w/ caps Ext w/ coils
123.300 5 18 14 11
123.075 5 24 21 12
122.800 5 24 16 10

Hopefully this week Zaon’s technical people will come back from
Oshkosh, and they'll have ideas to tackle this problem at the source.

-John

On Jul 30, 10:43 pm, "Tim Ward" > wrote:
> Not an EE, but it might be interesting to see how a the length of the llne
> to the battery affects things. I have a suspicion that the radiating
> element is the power lead, rather than the antenna. They could be using a
> switching regulator for external power (not unreasonable if you want a wide
> input range and decent efficiency).
>
> See if, with the Zaon antenna and power cord at right angles, rotating the
> receiver antenna from parallel to the Zaon antenna to parallel to the
> power cord makes the problem worse.
> Sometimes it's useful to find how to make things worse, and that gives you a
> clue as to how to make things better.
>
> A different approach might be to supply your own regulator as a "battery
> eliminator" that goes in place of the battery, supplying a filtered nominal
> battery voltage.
>
> But if a little is good, a lot may be better. Try paralleling a 10 uF cap
> with what you have.
> Keep increasing the capacitance until it doesn't help or gets worse.
> Some linear regulators will oscillate with too little capacitance on the
> input, but I would think Zaon would catch that.
>
> Also, is the power cord through the ferrite as many times as it will fit?
> The inductance is non-linear, it's proportional to the number of turns
> squared. So managing another turn or two through the toroid may help.
>
> Gosh, it's easy to come up with work I don't have to do myself.
>
> Tim Ward