Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

RF Problem

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Europa-List
View previous topic :: View next topic  
Author Message
jeff(at)rmmm.net
Guest





PostPosted: Sun Feb 12, 2006 4:45 pm    Post subject: RF Problem Reply with quote

HI All,
I remember this was discussed before, but to know resolution as I
recall. I Have been fighting an RF problem with my I-Com radio. The RF
is obviously getting into the ground as even the trim LED's are
effected. I have a Stratomaster engine monitor from MGL that seams to
work great until I hit the push to talk button. It then goes black and
the trim and Navaid LED's go crazy as well. I have a Bob Archer antenna
in the tail and the radio sounds clear and transmits well. When tested
with any other antenna the same thing occurs. The power to the antenna
is about 7 watts and there was only about a half a watt or less coming
back on the shield when tested. I made sure some time ago that the com
RG cable to the antenna was isolated from any other cables. We have
checked, and all grounds are good on the radio. I have been told to
install some ferrite RF suppressors on the ground and output of the
transmitter and to place them on the ground and power going into the
engine monitor. Before I order these have others run into this and have
you determined the cause and solution? Any Ideas are very welcome as I
have been scratching my head for a week!

Thanks in advance,
Jeff Roberts
A258 - N128LJ
Waiting inspection 1st week in March.


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
paul.mcallister



Joined: 09 Jan 2006
Posts: 177
Location: Waukesha, WI USA

PostPosted: Sun Feb 12, 2006 5:20 pm    Post subject: RF Problem Reply with quote

Jeff,

I have a Bob Archer antenna in the tail of my Europa. My trim control &
Navaids go nuts when I transmit and I haven't ever solved the problem. My
SWR is spot on, and the I never have a problem being heard, so the
transmitter is working well.

I am about to go down the ferrite bead route as well, I would be interested
to know how you get on.

Paul

--


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
View user's profile Send private message Visit poster's website
SPurpura(at)aol.com
Guest





PostPosted: Sun Feb 12, 2006 5:57 pm    Post subject: RF Problem Reply with quote

DOES YOUR RADIO SHARE A COMMON GROUND OR HAVE ITS OWN.

- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
flyinggpa(at)comcast.net
Guest





PostPosted: Sun Feb 12, 2006 6:21 pm    Post subject: RF Problem Reply with quote

Quote:
DOES YOUR RADIO SHARE A COMMON GROUND OR HAVE ITS OWN.

I was thinking the same thing. The Navaid is having a voltage problem. Make sure the radio has "lots" of wire on the power side. My BENDIX/KING called for two # 18 wires on both the + and - side. I think "your problem" is what they were trying to avoid. It never hurts to have to much wire size. (make it bigger)


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
n3eu(at)COMCAST.NET
Guest





PostPosted: Sun Feb 12, 2006 8:03 pm    Post subject: RF Problem Reply with quote

Quote:
I was thinking the same thing. Make sure the radio has
"lots" of wire

Quote:
on the power side. My BENDIX/KING called for two # 18
wires

Quote:
on both the + and - side. I think "your problem" is
what they were

Quote:
trying to avoid. It never hurts to have to much wire size.
(make it bigger)

Quote:


Two wires for +14V IN and GND are for redundancy. Rather
common in avionics boxes. I'm afraid lack thereof will not
solve the orig complaint. In plastic airplanes, the
radiated field is a strong, vigorous one, easily affecting
other electrical items. In aluminum planes, those affected
items are significantly shielded by the airframe. I know
this from me little handy field strength meter, while
xmitting, with the meter inside my aluminum plane, vs.
sticking it out the window in better line-of-sight from the
xmitting antenna. It's needle can peg with a resounding
click!

I'd first try the ferrite suppressors to trap the EMI
radiated to wiring of affected devices. Those things abound
everywhere these days from wall-brick "switching power
supplies" to charge the battery in consumer devices, through
those now found on the RF cable feeding digital, high-def TV
sets or digital cable boxes.

Reg,
Fred F.


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
jeff(at)rmmm.net
Guest





PostPosted: Sun Feb 12, 2006 8:45 pm    Post subject: RF Problem Reply with quote

Paul,
I'm going to remove the panel and have the local avionics shop that
wired it install the ferrite beads where I mentioned. As soon as I
reinstall it I'll let you know. I guess I can live with it to but I'd
rather fix it now if possible.
Thank you all for your comments.
Regards,
Jeff
A258 - N128LJ
Waiting inspection 1st week in March

On Feb 12, 2006, at 7:15 PM, Paul McAllister wrote:

[quote]
<paul.mcallister(at)qia.net>

Jeff,

I have a Bob Archer antenna in the tail of my Europa. My trim control
&
Navaids go nuts when I transmit and I haven't ever solved the problem.
My
SWR is spot on, and the I never have a problem being heard, so the
transmitter is working well.

I am about to go down the ferrite bead route as well, I would be
interested
to know how you get on.

Paul

--


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
n9zes(at)verizon.net
Guest





PostPosted: Mon Feb 13, 2006 5:52 am    Post subject: RF Problem Reply with quote

Jeff,

I have a Bob Archer antenna in the tail of my Europa. My trim control &
Navaids go nuts when I transmit and I haven't ever solved the problem. My
SWR is spot on, and the I never have a problem being heard, so the
transmitter is working well.

I am about to go down the ferrite bead route as well, I would be interested
to know how you get on.

Paul

---> I've had a bit of experience with RF problems, being a ham operator for the past decade or so, both with a 5 watt 144MHz handheld and also a 150 watt SSB HF radio. The wierd part is the 5 watt radio caused more issues than the big rig. I could wipe out every TV in our house with it.

The problem is not with the transmitter, or the SWR of the antenna. The problem is with other wiring, like the trim servo leads, picking up the radiated power and bringing it back to whatever is there. The solid state components in the 'box' act like a diode rectifier (a.k.a. crystal radio) and that power just overloads the circuitry. Most solid state electronics today is pretty well wide open to RF interferrence. Telephones are usually really bad, TV's, alarm systems, touch lamps, etc. are great at getting RF into them.

Part of the problem is the Europa itself. Since it's glass, the fuselage offers no internal shielding of other equipment from the radio transmissions like a Spam Can would.

The other problem is that any leads to servos, lighting, etc. will pick up the transmitted power, and be especially bad if the lead lengths are a multiple of the frequency (in 1/4 wavelengths).

A few solutions to try:

1) Make sure the radio chassis is grounded well to the airframe ground bus.
2) Make sure you are using good coax for the antenna lead (double shielded if necessary - foil and braid)
3) Get a ferrite bead assortment (Amidon is one brand). The ferrites do NOT go on the radio, but on everything else that is affected. This would mean that signal and power leads to trim systems, engine monitors, etc. all need to have beads or torroids applied.
4) In worst case situations, you need to actually shield the affected equipment itself, which means building a grounded box around the device from copper sheet, etc.

Chris


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
topglock(at)cox.net
Guest





PostPosted: Mon Feb 13, 2006 10:26 am    Post subject: RF Problem Reply with quote

Jeff,

I'm using the same setup Icom/Archer. My coax runs through a 1" x 2"
channel in the left of the fuse, along with the transponder coax, left
wing wiring and a couple of other power wires. You've ridden in the
bird and, as you probably know, there is no interference, at all. The
only time I had a probelm, was with the mic going to open and affecting
the trim, tripping the breaker. That turned out to be a short in
intercom wiring. Once it was fixed, the problem went away. I'd check
all other connections, including grounds, just to be sure they are all
good. Other than that, I'm stumpped, but that's not hard to do... Smile

I know you're close to first flight. Keep us apprised. Hope to see you
at Sun-N-Fun...

Jeff - N55XS
141 hours

JEFF ROBERTS wrote:

Quote:


HI All,
I remember this was discussed before, but to know resolution as I
recall. I Have been fighting an RF problem with my I-Com radio. The RF
is obviously getting into the ground as even the trim LED's are
effected. I have a Stratomaster engine monitor from MGL that seams to
work great until I hit the push to talk button. It then goes black and
the trim and Navaid LED's go crazy as well. I have a Bob Archer antenna
in the tail and the radio sounds clear and transmits well. When tested
with any other antenna the same thing occurs. The power to the antenna
is about 7 watts and there was only about a half a watt or less coming
back on the shield when tested. I made sure some time ago that the com
RG cable to the antenna was isolated from any other cables. We have
checked, and all grounds are good on the radio. I have been told to
install some ferrite RF suppressors on the ground and output of the
transmitter and to place them on the ground and power going into the
engine monitor. Before I order these have others run into this and have
you determined the cause and solution? Any Ideas are very welcome as I
have been scratching my head for a week!

Thanks in advance,
Jeff Roberts
A258 - N128LJ
Waiting inspection 1st week in March.

















--


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
jeff(at)rmmm.net
Guest





PostPosted: Mon Feb 13, 2006 1:38 pm    Post subject: RF Problem Reply with quote

Hi Jeff, hows it going? Yes I agree the ground is the most likely place
it's getting in but I'v run a second ground to the radio rack the
engine monitor the trim and still can't get rid of it. I'll try the
ferrite beads next. I too ran all my coax down the opposite side
keeping them away from the others wires. I'll be taking the panel to
Ron Dupler at the local avionics shop and letting him have a stab at it
as myself and two other local plastic plane builders are all stumped.
Looks like Paul McCallister is having the same problem.
I probably wont have the hours flown off by Sun & Fun but I still may
be there. I have a friend that lives not far from Lakeland thats
expecting me. I'll let you know or call your cell then.
Thanks, and we'll let you know of the first flight.
Jeff
A258
On Feb 13, 2006, at 12:06 PM, Jeff B wrote:

Quote:


Jeff,

I'm using the same setup Icom/Archer. My coax runs through a 1" x 2"
channel in the left of the fuse, along with the transponder coax, left
wing wiring and a couple of other power wires. You've ridden in the
bird and, as you probably know, there is no interference, at all. The
only time I had a probelm, was with the mic going to open and affecting
the trim, tripping the breaker. That turned out to be a short in
intercom wiring. Once it was fixed, the problem went away. I'd check
all other connections, including grounds, just to be sure they are all
good. Other than that, I'm stumpped, but that's not hard to do... Smile

I know you're close to first flight. Keep us apprised. Hope to see
you
at Sun-N-Fun...

Jeff - N55XS
141 hours

JEFF ROBERTS wrote:

>
>
> HI All,
> I remember this was discussed before, but to know resolution as I
> recall. I Have been fighting an RF problem with my I-Com radio. The RF
> is obviously getting into the ground as even the trim LED's are
> effected. I have a Stratomaster engine monitor from MGL that seams to
> work great until I hit the push to talk button. It then goes black and
> the trim and Navaid LED's go crazy as well. I have a Bob Archer
> antenna
> in the tail and the radio sounds clear and transmits well. When tested
> with any other antenna the same thing occurs. The power to the antenna
> is about 7 watts and there was only about a half a watt or less coming
> back on the shield when tested. I made sure some time ago that the
> com
> RG cable to the antenna was isolated from any other cables. We have
> checked, and all grounds are good on the radio. I have been told to
> install some ferrite RF suppressors on the ground and output of the
> transmitter and to place them on the ground and power going into the
> engine monitor. Before I order these have others run into this and
> have
> you determined the cause and solution? Any Ideas are very welcome as I
> have been scratching my head for a week!
>
> Thanks in advance,
> Jeff Roberts
> A258 - N128LJ
> Waiting inspection 1st week in March.
>
--





- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
n3eu(at)comcast.net
Guest





PostPosted: Mon Feb 13, 2006 2:58 pm    Post subject: RF Problem Reply with quote

Chris Beck wrote:

Quote:
The weird part is the 5 watt radio caused more issues than
the big rig. I could wipe out every TV in our house with
it.

Quote:

Chris, ain't that fun. My 2.3W-carrier VHF handheld, at 20

feet from small (cheap) TVs, will briefly make the screen
black and kill audio. But just inches anywhere from a new,
big Sony flat-screen digital -- absolutely nothing. It may
be as much circuit design as shielding of the "victim"
device, as interference I guess is intolerable for the big
bucks you have to pay!

Quote:
2) Make sure you are using good coax for the antenna
lead (double shielded if necessary - foil and braid)

I would consider "bettering" the coax a last resort. If I
take said handheld and xmit in the vicinity of a RG-58 patch
cable (unterminated) at the input of my 200mHz oscilloscope,
coax about antenna length, I might see like only 10mV a few
feet from this cable.

Since receive is the reciprocal of xmit in these matters,
the corollary is shielding the input wires to the victim
device, single or multi-conductor as convenient. The shield
would not be a ground path, just grounded at the instrument
end, I would say.

Quote:
3) Get a ferrite bead assortment (Amidon is one brand).

Ferrite beads or small toriod donuts have a frequency spec
and may be less than what we need if small. A larger donut
allows spiral winding (twice at least) around the core.

If instead of RG-58 in above test, I then use plain, solid
wire. Again about 1/4-wavelength. Scope sensitivity will
have to be readjusted...a lot! If I lengthen the wire to
random length (nonresonant), way down. If I then take a 1"
ferrite cylinder with even 3/8" ID, pass the wire through it
and near the BNC input, scope trace is way down. Make one
spiral turn around the ferrite, way down again. So,
ideally, the wire should be spiral-wound around a donut a
couple times. For instrumentation as the victim device, I'd
try input wires first, like sensor wires. Ten of millivolts
on the 14V or ground wire shouldn't matter much.

Google: ferrite core suppressor, for ideas, sources, and
white papers on the science. Rather than undo wiring, I'd
first try the plastic encased clamp-on suppressors. One may
be able to liberate one off a consumer device wall charger,
and affix it around the wire bundle to the instrument. To
see if we're going in the right direction.

Reg,
Fred F.


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Europa-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group