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tkirk
08-13-2007, 02:20 PM
I have the trutrak ADI-1 and have a problem. When I key the mic, the ADI indicator jumps down and holds until I release the mic key, then the indicator goes back to normal. Any one else experience this?

I have an SL40, a Bob archer wing tip antenna (left wing), and the trutrak servor is in the right wing. The servo and antenna (RG-400) wires are bundled together coming from behind the panel and down the firewall and then back to the spar where they split. Do I need to try to separate the servo and antenna wires, or is there another possilbe cause??

hevansrv7a
08-13-2007, 04:20 PM
I have the TT DigiFlight II with altitude hold. When I was using the Archer wingtip antenna for comm, keying the mike would cause the TT to pitch up dramatically. For that and even better reasons (range and clarity) I switched to a Comant on the belly and the problem went away. It may not have been the Archer itself, but the way I ran the wires in proximity. The Comant wire is not in the same bundle as the TT, but the Archer wire was/is. I had the Archer checked for stray energy and all that technical stuff and it was OK, so my tentative conclusion is that the bundling of the wires was the real culprit. I did need the much better performance of the Comant, though, so I solved two for the price of one. I hope this helps.

jeff beckley
08-13-2007, 04:23 PM
At first I would not suspect RF interference but more on the side of a grounding issue. An improper ground some where in the system can wreak havoc on diagnosing goofy indicator problems. First I would make a temporary power cable just for the ADI. Both power and ground and connect it directly to a power source. Observe if this corrected the problem. If it does then you have somewhere to start.
Let us know how it works!

tkirk
08-13-2007, 08:11 PM
Thanks for the replies. I was already thinking about a belly mount for the same reasons you state.

As far as grounding, I will try a different harness but I don't think that will be the problem. I have a common ground block (48 tab from B&C) and was very careful connecting all of the grounds because I did not want any noise.

kentb
08-15-2007, 11:03 AM
When I transmit on my SL30/wing tip antenna, I see my fuel level on my AFS engine monitor take a dip. The longer I talk the lower it goes. Some of the other sensors are also effected to a lesser degree.
Before I figured this out it gave me some tense moments. All thing would be going along fine and as I approached the airport area, I would transmit my location. The AFS would announce to me "fuel low". :( I would look over at the indicator and see that it was no longer green, but had turned yellow. The closer I got to the airport the lower my fuel would go, until on final it might be in the red. :eek:
By the time I had finished taxing it would be back in the green. :)
I haven't found the fix for this yet and don't have a problem on my 2nd radio, GNS430/bent whip. I just have been avoiding transmitting on the 1st radio.

Kent

DGlaeser
08-15-2007, 01:35 PM
I believe that somewhere in the TT documentation they warn against running the A/P disconnect wire (assuming you have one) in parallel with a COMM antenna wire. Running it across a COMM wire is OK.

AV8rDoc
08-15-2007, 01:42 PM
I too have an interesting phenomenon that seems to be associated with the Archer wingtip Com antenna.

When I key the mic to transmit, my Van's manifold pressure gauge and Van's Ammeter gauge go all the way off the scale :eek: The gauges return to normalcy when I release the mic switch. It seems to affect the gauges differently depending on which com frequency is selected. It happens with or without the engine running and with or without the alternator turned on and seems to have nothing to do with battery voltage.

The com antenna cable is bundled with the other instrument panel wiring until it gets to the center console and then runs into the wing with the nav light/strobe/landing light wires. I wonder if it is related to the antenna wire being bundled with the instrument panel wiring or if it is related somehow to the Archer com antenna itself :confused: .

I like the fact that my com antenna is hidden and not hanging in the slipstream, but I am toying with replacing it with an external whip on the belly. Does anyone have a feel as to whether the 'wierdness' with the Archer com is related to the antenna itself or due to wiring/bundling issues?

tc1234c
08-15-2007, 02:25 PM
Talk about RF interference, I have an interesting experience. Last March I did first flight of a RV-6A. Each time I keyed the mike, the ELT got triggered. I heard the noise but was too busy to hunt it down. When I landed the FBO guy run over to inform me of the ELT transmission. On my second flight that day, I kept my finger closed to the remote ELT reset button. Each time I keyed the mike, I had to reset the ELT. Subsequently the owner reroute the cables and the problem went away (at least for the local UNICOM frequency).

plehrke
08-15-2007, 03:55 PM
When I key the mic to transmit, my Van's manifold pressure gauge and Van's Ammeter gauge go all the way off the scale :eek: The gauges return to normalcy when I release the mic switch. It seems to affect the gauges differently depending on which com frequency is selected. I have the same issue but only happens when I have the nav lights on. I get a full scale deflection of the ammeter when keying the PTT. I am using a belly mounted Comant whip antenna.
I thought it might be an RF interferance issue with the ammeter wire. I tried shielding the ammeter wire from the radio (it was routed directly behind it) and got very little effect.
Based on some of the suggestions here I may try checking the ground on the nav lights. They are grounded in the wing where as everything else is grounded at the firewall. I installed a couple of studs to put a grounding strap between the wing and the fuselage but did not install it due to very little ohms when checked with a ohm meter between the wing and the fuselage.

tkirk
08-15-2007, 04:10 PM
I separated the antenna wire from the bundle of wires coming from the panel and all the way down the FW, and the TT deflection was about 1/4 the amount it was before. The antenna wire is now separated from the other wires from the SL40 all the way to the wing root. At the wing root, the antenna wire joins the taxi light, position light, and future pitot heat wires in the wing. If I get some time, I think I will pull the antenna wire all the way out of the wing and separate from all other wires then reconnect to the SL30 and see if the problem goes away.

I also noticed that the ray allen trim indicator jumps from neutral to the bottom of the indicator when the mic is keyed (trim servo does not move).

BTW, I don't have an autopilot disconnect wire. Also, the antenna seems to be well grounded to the air frame as per the installation instructions.

jeff beckley
08-15-2007, 05:17 PM
I am telling you again to look for a ground problem. I feel more strongly that you have a ground problem with your radio now that you mentioned the ray allan indicator. I too had the indicator go nuts and also had the amp meter pull to the left when I keyed the mic. I also have a single ground block and I home ran all of the grounds back to this block and still had the problems all of you have mentioned. Before you pull all of your antenna wire out of the wing do a simple test by just running pos and gnd DIRECTLY from the TT to the battery. Key the mic and note the result.
Current flows from neg to positive and the radio pulls the most current when the mic is keyed. If the ground is not proper it will pull current anyway it can. It could be a connection directly behind the radio. Ground issues are a pain in the butt to track down.

tkirk
08-23-2007, 08:51 PM
I finally had some time this evening, so I disconnected the TT harness and ran pos and neg wires from the TT directly to the battery. Even after doing this, I still have the same problem as before. I am not sure what I will do next, but I am leaning toward a belly whip antenna.

WilburD2
08-24-2007, 03:33 AM
Have seen this sort of issue several times in the commercial world. Every time it was associated to the antenna itself. Either a breakdown of the antenna windings, corrosion build up between the antenna and its connector or a corrosion build up breaking the ground of the antenna to the airframe. Try a little scotchbrite and contact cleaner yet?

PaigeHoffart
08-24-2007, 06:26 AM
Have you checked the coax connection at the back of the radio? It's a solder type connection, and a cold solder joint on the shield or center conductor could cause some RF to flow on the outside of the coax. I'd also double check the coax connection at the antenna, a bad connection on either the center conductor or shield will have the same effect.

Another old Ham trick is to coil up about five turns of coax in a 2" diameter loop right near the feed point of the antenna. That should de-couple the coax from the antenna, and keep reflected RF from flowing on the outside of the coax.

I would also look for a friend or neighbor that had an SWR meter to check the SWR (Standing Wave Ratio) of the antenna. A high SWR (depends on radio but ROT is 2:1) could certainly make RFI worse, and might even damage the radio.

If you only had to worry about power leads, you could put a bypass capacitor (.01uF) across the power leads right where they enter the device, but with all the other wires going to the servo, you still have plenty of avenues for the RF to get in. I'd call TRU-TRAK before putting a bypass capacitor on any other lines.

Finally, do you have strobe or nav light wires running right next to the antenna? The method of routing, and the location of the antenna ground vs. where these wires cross will have a big impact on the amount of RF that flows on them.

-Paige

RV-8A

Lycosaurus
08-24-2007, 07:10 AM
I'll throw my 2 cents in as well ... check the grounding at the antenna itself. I believe that Bob Archer says to have a good ground interface at the wingtip for his antenna. How are you grounding it?

Another test you can try is to use another coax, and transmit using the elt antenna, which is a 1/4 wave over the fuselage as a ground plane. Hopefully you also have a good ground on this one, if not, then make sure the surface where the nut is being tightened is clear of primer/paint. You want the antenna shield to be grounded well at the antenna.

victor
08-24-2007, 08:48 AM
I had the same problem with my 9A before first flight in '03. MP and ammeter would go wacky when ppt button pushed. Delayed first flight over a month. After removing panel numerous times, talking to anyone I could bug for opinions, I called Vans. I think it was Gus that explained to me that the gauges(steam) are simple electromagnetic 1950's technology, are not shielded, and are affected by close proximity to RF radiating from radio. He said they removed the ammeter gauge(have voltmeter only) and did not put mp gauge in the prototype 9A because "it would upset the passengers".

I also thought it was com ant, coax, ant location, bad ground, or maybe global warming. I guess it's just the 50's auto technology,as Gus said, and can be ignored ,or removed, or you can spend bigger bucks and buy new technology instruments. :(

apatti
09-27-2007, 07:43 AM
I want to revive this thread because I am getting ready to install my autopilot servos and com/transponder antennas. It appears to me from reading this thread that the thing to avoid is running the com/xponder coax parallel with autopilot wires. They should cross at right angles to the extent possible.

What is less clear to me is whether there is a problem with locating the com/xponder antennas close to the autopilot servos. I am building an 8A wtih TT pitch and roll servos and want to mount the antennas (2 bent whips and a rod) on the centerline on the under-belly. I know I need antenna separation from each other (coms primarily). However, do I need to be careful how close the antennas are to the servos?

Also, for those of you who mounted an antenna on the centerline belly of an 8A... How did you deal with the lip down the middle where the two belly skins join?

Thanks,

scard
09-27-2007, 09:01 AM
Reading back through this thread, it seems to me that there may be a commonality with the Archer COM antenna. I'll add my data point: I WAS using an Archer wing tip antenna for COM2 and when I would transmit on some frequencies, the TruTrak autopilot would command a large pitch change. I abandoned the wing tip antenna for a Comant belly whip for better reception, and the issue is gone.

AV8rDoc
09-27-2007, 11:37 AM
I am in agreement with Scott that at least some of what has been described in this thread seems to be related to the Archer wingtip com antenna. I ran an experiment: I disconnected the coax in my wingtip from the Archer com antenna and connected it to a standard whip antenna that I borrowed from a friend. I did not change and wiring/bundling in any way. Now when I trigger the PTT I get only a very very minor 'flick' of the ammeter and the manifold pressure gauge.:)

HMMMM..... now I am debating if I should reconsider placing a standard whip antenna on the belly and getting rid of the Arcgher wingtip com. I do like that extra 0.00001 knot advantage of the Archer wingtip antenna though! And the plane looks 'cleaner' for sure. I was planning to upgrade my engine instruments in the next few months to newer technolgy anyways, so if I no longer have the ammeter and MP gauge weirdness maybe i'll stick with the Archer com.... Decisions, decisions...:confused:

Ok- here's another question for the group that may be related: I have been using an ICOM A200 com with the Archer wingtip com. When transmitting in the air the sidetone and my transmissions at times sound all distorted, but it does not happen when transmitting on the ground. I think it is related to my microphone picking up high background noise in the cockpit during flight, but could it be related somehow to an RF interference issue from the Archer antenna? What do you guys think?

kentb
09-27-2007, 12:17 PM
HMMMM..... now I am debating if I should reconsider placing a standard whip antenna on the belly and getting rid of the Arcgher wingtip com. I do like that extra 0.00001 knot advantage of the Archer wingtip antenna though! And the plane looks 'cleaner' for sure. I was planning to upgrade my engine instruments in the next few months to newer technolgy anyways, so if I no longer have the ammeter and MP gauge weirdness maybe i'll stick with the Archer com.... Decisions, decisions...:confused:



I have the AFS2500 engine monitor and capacitive fuel sensors in the tanks. When I transmit on my Archer my fuel level drops. FAST.
Scared me the first couple of time this happened and I didn't know why. As I approached the airport and started broadcasting my position, my fuel started going away. It takes awhile with not transmitting before it reads correct again. The closer I got to the airport the lower my fuel was and the AFS 2500 started letting me know I had a problem "FUEL LOW". I was preparing myself for an engine out approach as the gauges were in the RED!

Now that I understand what is going on I don't use my #1 radio for transmitting. I will be installing another bent-whip on the belly this winter.

Kent

apatti
09-27-2007, 03:03 PM
I am in agreement with Scott that at least some of what has been described in this thread seems to be related to the Archer wingtip com antenna. I ran an experiment: I disconnected the coax in my wingtip from the Archer com antenna and connected it to a standard whip antenna that I borrowed from a friend. I did not change and wiring/bundling in any way. Now when I trigger the PTT I get only a very very minor 'flick' of the ammeter and the manifold pressure gauge.:)



HHMMMM...I wonder if there is a high VSWR on some installations of the Archer antenna. I am not questioning whether the design of the antenna was done properly. However, there are many installation variables that could be affecting the VSWR. High SWR means a stronger reflected wave which could be coupling over into other instrumentation. Personnally, I don't think I would install an Archer com antenna without checking the SWR. Then again I am an old ham radio guy...

So far I am not hearing that there is any potential problem with locating the com/xponder antennas near the AP servos. I'll wait for more folks to hopefully respond.

Thanks all,

kentb
09-27-2007, 06:51 PM
HHMMMM...I wonder if there is a high VSWR on some installations of the Archer antenna. I am not questioning whether the design of the antenna was done properly. However, there are many installation variables that could be affecting the VSWR. High SWR means a stronger reflected wave which could be coupling over into other instrumentation. Personnally, I don't think I would install an Archer com antenna without checking the SWR. Then again I am an old ham radio guy...

So far I am not hearing that there is any potential problem with locating the com/xponder antennas near the AP servos. I'll wait for more folks to hopefully respond.

Thanks all,

When I transmitted on the Archer in the hangar, my FM radio picked up a lot of static. Didn't happen when I used the bent-whip.
The Archer was about 10 ft from the radio that the whip was about 20.

Kent

scard
09-27-2007, 08:59 PM
So far I am not hearing that there is any potential problem with locating the com/xponder antennas near the AP servos. I'll wait for more folks to hopefully respond.

Come to think of it, my COM1 (comant belly bent whip) antenna off of my 430W is almost directly below my pitch servo, NO problems.

elippse
09-30-2007, 01:14 PM
There are two very certain ways you can get stray rf energy into your avionics. One is due to the fact that braided cable, even dual braid, emits rf energy through the spaces in the braid, both magnetic and electrostatic. Don't bundle low-level signals in with high power signals of any kind, rf or AC/DC, and use the best available cable for your radios, the low loss, high isolation Andrew FSJ1-50.
The other comes from reflections from the antenna due to an unbalanced load or the coax not leaving the antenna perpendicular will cause antenna currents to run down the outside of your coax. To get rid of this, put clamp-on ferrites over the cable close to the antenna. Radio Shack or JameCo.

elippse
09-30-2007, 01:18 PM
The proximity of the ground below the plane when on the groud changes the radiation pattern of the antenna from what it is in free-space!

elippse
09-30-2007, 01:22 PM
Some of these antennas are not balanced which will cause the aforementioned antenna currents on the outside of the coax which then enters the cockpit. This often shows up as squeels or distortion in transmission on some frequencies. Ferrites!!!

Gordon Henry
10-30-2007, 08:08 AM
I have the same problem as so many others. I have the ADI Pilot II, an SL-30 and a Comant Antenna on the belly. Keying the mike with altitude hold engaged causes a pronounced pitch up. The liquid crystal display on the engine monitor also changes values as long as the mike key is depressed. Pitch servo wires are well separated from antenna coax. Have checked all grounds, remounted the antenna with a backing plate and plate nuts to improve the ground and have temporarily clipped jumper wires from all shields and grounds to the fuselage. Nothing works. Spoke to John at TruTrak and he was suprised to hear of a problem with the ADI Pilot. Apparently there were difficulties with provious models. He is working on some filters but is pretty busy with other projects. As a last resort I am going to have an avionics shop read the antenna with a wattmeter to see if there is excessive RF feed back.

Gordon Henry
(RV-7)

tkirk
10-30-2007, 12:34 PM
FYI.....I bought one of the Radio Shack ferrites, but saw no change. I have also ran +/- wires direct from battery with servo disconnected....no change. Is there a chance this might be a Tru Trak problem? The horizon needle on my ADI-I is scratching the glass, so I have to send it in to be repaired anyway. Maybe Tru Trak can check the filters then, too.

My fix was to install a belly mount, but have not done that yet. Now it sounds like it could be a waste of time and money.

KPmarc
10-30-2007, 12:42 PM
I had (have) two internal antennas in my Sportsman, both copper-foil dipoles with the ferrite beads. One is in the composite vertical stab, the other behind the baggage bay, where it's forced to make a very wide C shape as the top and bottom extremities curve with the fuse.

I've been fighting similar problems with my TruTrak DigiFlight IIVSGV...same pitch-up but only when transmitting on the lower third of the com band. I tried moving the coax away from the servos and wiring but that didn't help. I also had what I'd call poor reception on both antennas and even worse transmitting capability on the C-shaped antenna, as you'd expect.

Finally bit the bullet and installed external com antennas on top of the wing. Miraculous! Much better reception, no more autopilot interaction...all is finally right with the world. I have not seen a speed decrease, but I haven't more than a couple of data points on that. I'd give up a knot or two to be able to talk to ATC.

Wish I'd done this sooner.

--Marc

PS: My first TruTrak ADI also had the pitch bar rubbing the glass, circa early 2006. Seems to be a continuing problem.

N184DA
10-30-2007, 01:38 PM
For what it's worth,,
My (A project is till in the hangar and I have a similar issue of RF interference affecting the MAC Trim Indicators. I have an SL30, and a belly mounted, bent-whip comm antenna. I have checked all of the grounds, even re-ran a temp coax from the sl30 to the antenna in an effort to maximize the distance from the trim servos, relays, indicators, and wiring,,, all to no avail.

I was able to duplicate the interference using my handheld transmitter, as a sort of RF Probe,,, passing it over and near any of the Trim System components with the Tx button keyed. In my case, I was able to reproduce the symptoms in and around the relay deck's. I have both of them mounted aft of the pilot's stick, below the floor,,, using terminal strips to connect the myriad of wiring.

What I have not tried is to pull the airplane outside and away from the metal hangar.

Anyway, I have decided to live with it unless someone can give me a definitive solution.
Of course, when the day comes for the first flight, as one poster suggested,, that may "fix" the problem by providing airspace below the antenna and thus limiting any reflective action from the hangar floor.

Pilottonny
10-04-2008, 11:02 AM
It is now a year since the last post in this thread, but I am experiencing the exact problems you guys were having! I have an SL30 with a Belly whip antenna, that is exactly underneath the Tru Trak Pitch servo. When keying the mike, the servo pulls the stick back, a lot. The Dynons show no emotion at all when keying the mike. The voltage stays the same. As far as I can tell all ground connections are fine.

- I pulled the Disengage wire from the Tru Trak: no cure!
- Disconnected all the com wiring to the Intercom and used a jumper, to key the mike: no cure!
- I even disconnected the coax at the radio and antenna and used a coax, run well away from all other wiring: no cure!

Here is bunch of questions:

- What to do/test next?
- My plane is still in the garage (concrete floor with some rebar in it), could the signal be bouncing off the floor, causing this?
- Should the whip of the antenna be ?connected? with the center conductor of the coax? I do not get a reading on my ohm-meter when testing between the whip and the center conductor.
- How did all of you, complaining about this problem, a year ago, fix it?

Hope you guys can up with some answers.

Regards, Tonny.

breister
10-04-2008, 09:47 PM
Not an RV guy, but had exactly the opposite problem on my Lancair 235 a few years back - key the mike, nose pitched down! It was never awful, as the mike key was on the stick and after the first time I just "knew" to hold a little back pressure when talking.

Never found a solution. The model was a DCF-200 (which accepted analog signals, not NMEA).

I'm hoping it doesn't occur in my new Digiflight II VSGV in my 320 - first flight any day now.

TrutrakTech
10-06-2008, 08:39 AM
It is now a year since the last post in this thread, but I am experiencing the exact problems you guys were having! I have an SL30 with a Belly whip antenna, that is exactly underneath the Tru Trak Pitch servo. When keying the mike, the servo pulls the stick back, a lot. The Dynons show no emotion at all when keying the mike. The voltage stays the same. As far as I can tell all ground connections are fine.

- I pulled the Disengage wire from the Tru Trak: no cure!
- Disconnected all the com wiring to the Intercom and used a jumper, to key the mike: no cure!
- I even disconnected the coax at the radio and antenna and used a coax, run well away from all other wiring: no cure!

Here is bunch of questions:

- What to do/test next?
- My plane is still in the garage (concrete floor with some rebar in it), could the signal be bouncing off the floor, causing this?
- Should the whip of the antenna be ?connected? with the center conductor of the coax? I do not get a reading on my ohm-meter when testing between the whip and the center conductor.
- How did all of you, complaining about this problem, a year ago, fix it?

Hope you guys can up with some answers.

Regards, Tonny.

Hi Tonny,

I will assume you have an ADI Pilot II. You also probably have the plastic casing on the unit. We now have a metal casing we can put on it for you at no charge. This eliminates the pitch up when the mike is keyed problem. Just give me a call or send me an email and I'll get you an RMA#. Thanks!

Pilottonny
11-15-2008, 05:32 AM
Hello everybody,

As was promissed by TruTrak, they changed the casing of my ADI Pilot II from plastic to aluminium and sent it back. I installed the instrument today, gues what? no change! I realy hoped and expected that this would cure the problem.

What about the others that posted in this thread, how did you guys solve these problems? Most of the posts are more than a year old. Please let us know!

Lucas: I also sent you a private message.

Regards, Tonny.

SkywayCaptain
11-29-2008, 07:07 PM
I have had some experience with some of the problems listed on this thread.

Have the following installed in my 7...

SL-30
DigiFlt IIVS
Van's Gauges

I operate a HF ham radio in the aircraft as well and have the following advice...

The Van's ammeter is very sensitive. The wires between the gauge and the shunt block should be shielded or run a single coaxial wire instead. This will stop RF from creating current flow in the gauge feed wires during transmit. External comm antennas that are operating properly should not interfere with the ammeter in my exp. reguardless of the wire setup.

Com antennas should be mounted outside the airframe to aviod interference with avionics. "Rubber duck" antennas transmitting inside the airframe vastly increase chance of RFI.

Try not to mount your trutrak near your comm (or other) transmitter.

Make sure that your antenna is well grounded.

Use high quality coax to feed your comm transmitter. Cheap RG-58 can cause problems.

Ground all avionics to a single point to avoid ground loop problems.

Consider making a balun on your comm transmit line. RF can flow on the outside of the antenna feedline and cause interference. A cheap easy way to make a balun is to simply coil the coax about 5 turns in about a 1.5 inch diameter as close to the antenna as you can. This forms a RF choke that stops certain frequencies from traveling back up the coax shield and radiating interfering signals.

Some aircraft antennas will not have any electrical continuity from the whip to the center conductor of the connector as they may have an internal transformer or other impeadence matching device inside.

I have isolated all the RFI problems in my aircraft other than a slight pitch change when the autopilot is on when transmitting on 14mhz through a 65ft trailing antenna at 100 watts!

Good luck

the_other_dougreeves
11-29-2008, 07:55 PM
I have this same problem with the ADI Pilot II in our CT. I will begin investigating the coax runs and connectors first, then will try the metal enclosure on the AP head.

TODR

Pilottonny
11-30-2008, 09:18 AM
I had to send the Trutrak back again, still awaiting the return, after wich testing will continue. I am very pleased that TruTrak is not just leaving me in the cold with some stupid answer that I am doing something wrong, but are trying very hard to solve the problem.

Regards, Tonny.

edbooth
11-30-2008, 10:04 AM
A few years ago I had a RV-6 with a Rocky Mountain engine monitor installed. After I flew it a couple times, everytime I keyed the radio (KLX-125) the monitor went blank... A check with RM suggested I had RF bouncing around the cockpit. This was a simple check as I only had one radio. I replaced the BNC connector on the belly mounted antenna even though it looked OK and miracles of miracles...the problem went away. That RF is strange stuff !

Ed Booth, Trenton, SC
Builder and flyer RV-6, 7, 9,10

Pilottonny
12-13-2008, 12:25 PM
Well folks,

I got the Trutrak back again, earlier this week and testing continued. I tried everything I could think of. Here are some samples:

- Connected power and ground directly to the battery and disconnected all wires except for the pitch servo ones. Problem still there!

- Used the ELT antenna, on top of the fuselage instead of the belly-whip antenna. Problem is less severe, but not solved. Maybe the ELT antenna is less powerful than the belly whip?

- Wrapped the whole unit in aluminum foil, including the front (the only plastic bit of the casing now). But that does not make any difference either. This shows how desperate I am!

You can imagine that I am without anymore ideas of what to test next. Anybody got any idea what is causing this? Could it be the surroundings of the aircraft, i.e. the fact that the plane is still in the garage?

I have all the other avionics and wiring finished now, but I do want to solve this problem before I carry on. If I need to change any of the wiring, now is the time to do it, while I still have good access to it.

I appreciate all you replies, please chime in and give us your thoughts on this!

Regards, Tonny.

frankh
12-13-2008, 01:42 PM
There are some folks who wear tin foil on their heads...something about aliens..have you tried that?..:)


Whay I would do is make up a new coax with new ends on it..like an exension cord and connect the radio directly to both the ELT and the whip antenna.I'm thinking RF is escapting your coax or connectors somehow.

Frank

Pilottonny
12-14-2008, 06:56 AM
Today I put two new connectors on the coax and also put ferites on both ends of the coax (got them of an old computer cable).
Also ran a separate temporary 12 V wire to the servo, well away from the coax.

I normally test on 123,45. After trying some lower and some higher frequencies it apears that the problem is biggest in the mid-range frequencies and completely gone in the low frequencies.

I do not understand this anymore, especially because it is only the Trutrak that reacts! I must have wasted at least 40 hours messing around with this and all to no avail!

Frank I already made up a coax and connected it directly from the SL30 to the belly whip, well away from all other wires (although it was TV-coax, I did not have any other spare coax).

I don't even want to think of ordering new coax, connectors and wires, ripping it all out and reroute it, only to find out that it has not cured the problem!

Regards, Tonny.

Norman CYYJ
12-14-2008, 03:08 PM
Is your antenna properly bonded to the airframe at the base?

Pilottonny
12-15-2008, 12:06 AM
Norman,

Yes it is, it is attached with 4 stainless steel screws and I removed the paint to make sure it is properly grounded. The Ohm-meter does not show any resistence between the outside of the connector and the airframe. Also tried the ELT-Antenna. The ELT selftests the Antenna to be OK, so there can not be a problem with that antenna.

My antenna is installed under the AP-servo, but I have seen many pictures of the same setup and these people don't seem to have any problems.

I feared this was due to the fact that I have the servo wires in the same bundle with the coax, but other people have done this with no problem. Also when I tested with a separate coax, I kept it well away from all other wiring and the problem was still there.

I am now awaiting start of business in the USA and hope to hear from Trutrak.

Kind regards, Tonny.

breister
12-15-2008, 01:15 PM
Tonny,

Considering how many people have had this exact same issue (including me), I have to believe that something in the TruTrack system is subject to picking up and amplifying RF. As I said in my earlier post I had a similar problem, but my airplane pitched down instead of up - but then I remembered that in my installation I had followed the directions to reverse the direction of the pitch servo, so the problem then becomes identical to yours with the false command coming from the control head.

I also distinctly remember it happened more aggressively in different frequencies, so this also matches your description. In general, though, if I did not take manual control while transmitting it would depart from the correct attitude, and then over-correct once the transmit switch was released. It was almost as if some capacitor were "charging" while transmit was on, and "discharging" once the power was released.

Why this happens to some people and not others is a mystery, but that it happens to so many speaks of a design problem. In the way of these things (and I really like the TruTrack folks) it is probably something so small and innocuous that it has never occurred to them that whatever it is could POSSIBLY be the cause.

As I said before, I do really like their autopilots and have bought a second one. If I have the problem with this one, I will probably be bull-headed like before and just learn to anticipate and cope with it, while continuing to pester them for a fix.

N8RV
12-15-2008, 02:44 PM
As I read this thread, I was hoping that by Page 5 there would have been definitive resolution of this AP/Tx issue, but no.

I have an ADI Pilot II, SL-30 and Comant belly whip like others here. However, since I have yet to leave the ground, I haven't discovered any problems. I may have to play around with it before I fly for the first time.

FWIW, I do remember a cautionary note that Stein made regarding my TT unit. He specifically said that there was some issue with comm transmitting causing a pitch change in the AP, and that "TruTrak is working on a fix."

However, judging from the comments and experiences related on this thread, I wonder if TT is indeed working on a fix ...

Pilottonny
12-16-2008, 03:19 AM
Don,

Are the SL30 and AP installed and working yet?

If they are, all you need to do is: engage the AP, the stick should be solid. Than push the PTT button and see what happens. If nothing happens, you want to make sure the AP is working correct by lifting the tail up and the stick should move. Also you want a handheld or any other radio to check if the Radio is transmitting.

Let us know what you find out.

If Stein has said there is an issue with it, that means it is not something I am doing wrong, :) but it also means that it may be difficult to cure! :mad:

I am still hoping to get an answer from Lucas real soon now, because I need to get on to new tasks, but can't until this problem is cured.

Regards, Tonny.

N8RV
12-16-2008, 07:16 AM
Yes, Tonny, I need to check the systems. At this point, I just finished wiring and plumbing everything and am shifting my focus to body work -- you know, sanding and priming and sanding and priming and ... well, you understand.

However, I'll probably check things this weekend. I need to verify that my antenna connections are all sound (haven't figured out how best to do that) and I'll try the transmit-while-lifting-tail test and report back.

Wicked Stick
12-16-2008, 08:05 AM
I too encountered the exact same problem.
ADI Pilot II, Commant Bent whip on the belly, SL-30 & Icom A210 both do it.

With altitude hold engaged, and key the mic and the pitch servo goes nuts. :eek:

I sent it back to TT and they removed the plastic casing and installed the newer aluminum box and if memory serves they said they added something else inside as well.

When it came back, I re-installed it (had to re-route pitot static lines because the ports on the back are now in a different location) and then turned it all back on to try it.

It still moves the pitch servo when the mic is keyed up, but to a much lesser degree than before. :(

So, it seems they are moving in the right direction, but still have more to fix.

Pilottonny
12-16-2008, 08:16 AM
Thanks guys for sharing this with us here. At least I know not to continue searching or start ripping out my wiring, I wasted to much time on this as it is.

I also had a bit of a strugle with the Pitot and static lines, because of the different location of the connections. But because I use the plastic tubes I could alter the tubing without to much hassle. Fortunately I had plenty of spare tubing.

BTW have you run your coax together with the Servo wires, or are they well apart?

Regards, Tonny.

breister
12-17-2008, 01:04 PM
Don,

Are the SL30 and AP installed and working yet?

If they are, all you need to do is: engage the AP, the stick should be solid. Than push the PTT button and see what happens. If nothing happens, you want to make sure the AP is working correct by lifting the tail up and the stick should move. Also you want a handheld or any other radio to check if the Radio is transmitting.

I'm gonna sound like a rainy day here - but I tried exactly that years back with my original, and the problem did not manifest on the ground.

Best test? Make sure that you have the autopilot "vertical torque" setting as low as you can set it and still have it provide enough torque to move the nose up and down as it should. Then, when you are airborne and the autopilot is on "Altitude Hold" key the mike - just be prepared to use a little force to keep the nose level.

You will know immediately if you have this issue.

If Stein has said there is an issue with it, that means it is not something I am doing wrong, :) but it also means that it may be difficult to cure! :mad:

Amen! I used to think I was the only one - even flew out to the factory. To their credit, they spent most of a day; even replaced my unit; and went flying with me. It did not solve the problem.

Keep us posted on your results!

Bill

Pilottonny
12-17-2008, 02:32 PM
Bill,

that sounds not good at all! I am not going to fly with an AP that I know, is not working properly! Flying out to the factory is not an option for me (from Belgium). The problem needs to be cured before I build on anyway! After all the effort I put in, adapting the controls, installing brackets, wiring, installing the servo's, cutting my panel, testing, etc., there is just no way back! Trutrak will have to make this work!

This problem so far has cost me over $ 600,- in shipping cost, coax connectors, wire, import duties and VAT, (on the return parcels, because the Belgian Customs charge it anyway, even with the paperwork saying it is a free repair). So far I have paid all these costs, without arguing with Trutrak about it, because I was under the impression, from Lucas, that Trutrak were also doing their best and were going to cure this problem pretty pronto.

Yesterday Lucas asked me at what frequencies the problem occurred. I haven't heard from him since my answer yesterday. I will give him some more time before I start calling.

Thanks for sharing, maybe....., maybe... your problem will get solved when they find the cure for my problem, who knows.

Please monitor this thread.

Kind regards, Tonny

L.Adamson
12-17-2008, 02:59 PM
The problem needs to be cured before I build on anyway! After all the effort I put in, adapting the controls, installing brackets, wiring, installing the servo's, cutting my panel, testing, etc., there is just no way back! Trutrak will have to make this work!


One thing to think about. Over the years here and on the Matronics forum (I've been reading these for about 14 years); I've seen many complaints against the manufacture, where the actual problem was some kind of a slight error due to the installation. Just last week there was one on this web site, in regards to a Garmin and Icom radio. Turns out the Icom had problems because of a small short due to two wires being too close. The airplane builder had about had it with the radio, but it all turned out well; after getting no where with the Icom rep. Afterall, how's the rep going to know an install error?

I screwed up my own Tru-Trak install, because I wired a "mirror image" on the annunciator light/ power switch. Once I figured out what it was, it works just great. Stein, even sent a free replacement light and plug, which obviously didn't cure the problem.

What I'm pointing out, is that we often figure it's up to the manufacturer to set things straight, no matter what. Yet the problem may or may not be their problem to begin with. Since we install the devices our selves, instead of being required to have them installed by a factory rep; sometimes there is only so much a manufacturer can do. Especially when the installation is far from any representative.

L.Adamson

Pilottonny
12-17-2008, 04:07 PM
"L",

I was assuming it was me who caused the problem, until I heared that a lot of other builders are having exactly the same problem.

I would love to hear that I have done something wrong, than all I need to do is put it right and it will work, right?! I tried so many things, had so many sugestions, but nothing worked, so far.

Please, please, make my day and tell me what I am doing wrong, that is also what I want Trutrak to tell me.

Regards, Tonny

L.Adamson
12-17-2008, 04:50 PM
This won't make you feel better, but the RV9A that I flew for many hours before finishing my 6A; also has a TruTrak ADI II, with Coment belly antenna, and a Garmin SL-40 radio along with dual Dynons. It doesn't exhibit any of these pitch problems.

In the mean time, I'll be giving it some thought.

L.Adamson -- RV6A

mannanj
12-17-2008, 07:20 PM
"L",

I was assuming it was me who caused the problem, until I heared that a lot of other builders are having exactly the same problem.

I would love to hear that I have done something wrong, than all I need to do is put it right and it will work, right?! I tried so many things, had so many sugestions, but nothing worked, so far.

Please, please, make my day and tell me what I am doing wrong, that is also what I want Trutrak to tell me.

Regards, Tonny

Tonny:

I understand your frustration with the current setup.

About 5 years ago when I was dreaming of what I wanted in my panel, I decided on the Tru-Trak Digiflight II VSG and the Grand Rapids EFIS. At the time they were the only ones that could "talk" to each other. I couldn't afford both at the time so I opted for the Tru-Trak and decided to wait on the EFIS.

Two and a half years ago after I completed Phase One Testing, I discovered that with the autopilot on, when I transmitted on the Comm Radio at about 127.000 Mhz and above, my autopilot would push nose down. The higher the freq. --- the more nose down.

I contacted Tru-Trak and they suggested that I shield the "Control Wheel Steering/Auto-pilot disconnect switch". That didn't help.

In their defense, I have an older style stainless bent whip comm antenna with the ring connector; not the BNC style of the later antennas.

I have made sure that the antenna/autopilot signal wires cross at 90* angles where they have to cross.

Since I seldom fly IMC, this is not a very big problem for me. I just anticipate it and hold the stick back when I transmit,as the PTT switch is on the stick of my RV-8.

I have other issues that I've discussed with Andrew and Lucas both of whom promised to get back with me about a month ago and I've heard nothing from them.

Tru-Trak: You need to address these issues and follow up on your promises to call back to avoid further "bad press".

I have stood by you and recommended your products to a lot of people. I'm not trying to "bad mouth" your autopilots. You have a good product, but I believe that you need get on top of this---the sooner the better.

breister
12-17-2008, 08:47 PM
Well said. I'm not interested in bad-mouthing anyone, either - as I said, I bought another one despite the small annoyance.

Really, if your PTT switch is on the stick it just isn't a big deal. Just hold back a bit on the stick while talking. After a while I completely forgot it was an issue. The rest of the time the autopilot was spot-on.

And, it may very well turn out that it was an installation issue all along. Our airplanes are very small, and wires run parallel in many places.

If nothing else, it gives you extra incentive to keep your transmissions short!

:D

L.Adamson
12-17-2008, 09:26 PM
Well said. I'm not interested in bad-mouthing anyone, either - as I said, I bought another one despite the small annoyance.

Really, if your PTT switch is on the stick it just isn't a big deal. Just hold back a bit on the stick while talking. After a while I completely forgot it was an issue. The rest of the time the autopilot was spot-on.

And, it may very well turn out that it was an installation issue all along. Our airplanes are very small, and wires run parallel in many places.

If nothing else, it gives you extra incentive to keep your transmissions short!

:D

This is all interesting; but I do have quite a few hours in three different RV's with TruTrak altitude auto-pilots along with PTT switches in the stick, and none have exhibited this problem.

L.Adamson

SteinAir
12-17-2008, 10:24 PM
Hi Guys,

My names been tossed around here a bit since I've been involved with a majority of you on your AP installs. I've kind of tried to keep working this with each of you and do what we can.

However, I thought I would post something publicly to let you know that TruTrak is not ignoring you...quite the opposite. Larry's post actually is what drew me to post.

I know it's aggravating for you if you have these issues, but let me tell you it's hundreds of times (maybe thousands) more aggravating for us a dealers and TruTrak as the mfgr. Here's why. Out of the thousands of AP's that TT has flying, only a statistically very few exhibit these issues. Of those few, we usually find that 99% of the time it is install error of some sort, whether the builder knows it or not. These can be excruciating to troubleshoot, as each installation of each persons airplanes is different, and not being able to be right in front of the plane makes it even harder. I'm not saying it's the case all the time, but almost always in the end it is - what is really hard is to find the trigger for the problem because it can be so remotely far away from the core AP that it just makes it really tough.

Anyway, I don't have much to say to immediately help you, other that to let you know that everyone is looking at each issue when they come up...not much of a warm/fuzzy I know, but it's the best I've got at the moment.

My 2 cents as usual!

Cheers,
Stein

Wicked Stick
12-18-2008, 08:42 AM
Has anyone an educated guess as to why it's always an issue with the pitch servo and not the roll ? Is this showing up only in certain RV models ?

Most of us here have no intention of bad mouthing TT, and for me, sharing info like this can only help to collect comman facts about the issue and hopefully it will eventualy come to a resloved conclusion.

SteinAir
12-18-2008, 11:26 AM
Has anyone an educated guess as to why it's always an issue with the pitch servo and not the roll ? Is this showing up only in certain RV models ?

Most of us here have no intention of bad mouthing TT, and for me, sharing info like this can only help to collect comman facts about the issue and hopefully it will eventualy come to a resloved conclusion.

Yep...it's typically because the pitch servo ends up closer to a transmitting antenna.

It hasn't been model specific either.

MNForrest
12-18-2008, 12:00 PM
Is there a way you could temporarily install a new run of coax and an identical antenna - even externally while on the ground - to test the location, cable run, etc? Maybe you have been there already.

Pilottonny
12-18-2008, 01:45 PM
Although I said I was not going to do anymore testing, I went to see an Amateur Radio guy today, who works on Aircraft radios occasionally. He suggested that the servo picks up the interference from the coax or antenna (especialy if the antenna is not 100% matched to the radio freqency, which I doubt for a Commant antenna) and sends it back along the wires from the servo to the AP-unit. He said a cure would be:... looping the cable through a ferrite "ring"! Not the coax, but the servo wires! Since the wires are not long anough for looping them through a ring, I picked up a few "sanp-around-two-halves-ferites" from a local electronics shop, to try if they make any difference. If they do, maybe I schould make my wires longer and try the "ring".

Today Lucas sent me an email saying they are trying to duplicate the problem in their shop, to do some more tests. Maybe this will not only solve my problem but also the problems of all the others that chimed in, the last couple of days. Obviously, also Trutrak want to solve this.

Regards, Tonny.

Brantel
12-18-2008, 01:56 PM
Just a note. Ferrite cores/rings etc. are made from various materials and they are not all the same. You need one that is made for the range of frequencies your working with.

RF traveling back down a feedline is a very common problem with transmitters. Ham's use all sorts of techniques to fight this issue.

Just because your antenna is a Commant does not mean that it will be perfectly balanced across the bandwidth. 1/4 wave antennas like those we use are almost impossible to get 1:1 SWR using coax as a feedline and the airplane as a ground plane.

N8RV
12-18-2008, 02:47 PM
Yep...it's typically because the pitch servo ends up closer to a transmitting antenna.

It hasn't been model specific either.

Well, considering that my Comant antenna is mounted almost directly beneath the ROLL servo (pitch servo is clear back by the elevator bellcrank), I would expect my setup to have roll interference and NOT pitch by your theory, Stein.

I'll give it a whirl this weekend and report back.

FrankK90989
12-18-2008, 03:01 PM
Tony,
Here is a photo of the balun I used.(befor heat shrink) A Jim Weir design. one he put a awful lot of work in to. if you can tame your Rf I think your problems will go away.:)
PS. used on the antenna end of the coax
http://img255.imageshack.us/img255/3373/img1609rxj2.jpg

Wicked Stick
12-18-2008, 06:06 PM
Yep...it's typically because the pitch servo ends up closer to a transmitting antenna.

It hasn't been model specific either.


I have an RV-8. As you know the pitch servo is behind the rear baggage compartment. Distance-wise, the Roll servo is located much closer albeit off to the side.

mannanj
12-18-2008, 06:32 PM
Today Lucas sent me an email saying they are trying to duplicate the problem in their shop, to do some more tests. Maybe this will not only solve my problem but also the problems of all the others that chimed in, the last couple of days. Obviously, also Trutrak want to solve this.

Regards, Tonny.

Lucas; Tru-Trak; et al. After Christmas, I'll fly out to AR for a couple of days so you can experiment with my RV-8 set-up to try to determine the problem if you guys will buy the gas and put me up in a Motel that isn't too much of a flea-bag. 770-519-4999.

N8RV
12-19-2008, 04:16 PM
OK, I went to the hangar today and the first thing I did was flip on the master, turn on the A/P and see what happened when I keyed the mike.

There was a definite pitch down and there also seemed to be some roll effect as well. I tried every combination and found that, with altitude hold off, there was still some slight effect on the roll servo.

Of course, I then referred back to Stein's notes which noted that, "on the bench there was a tendency for the A/P to cause a descending right turn when the mic was keyed," and that TT is aware of the problem and working on a fix.

So, once again, STEIN is absolutely correct (not that I had any doubt).

Also, what that tells me is that the problem is likely NOT necessarily related to the type of antenna, the routing of the antenna coax or the location of the antenna if it happens on the bench as well as in some planes.

Personally, I'm not going to worry about it. My hand's on the stick when I key the mic, so it's apparently not much more than an inconvenience. However, if TT figures out a reliable solution, it would be nice to not have this irritiation.

mannanj
12-19-2008, 07:23 PM
Guess I shouldn't have had a couple of beers before I made the offer to Lucas to fly to Arkansas. Looks like they may take me up on it.;)

They have a good product and I'm willing to help solve this glitch. The problem only affects an extremely small portion of their autopilots, and as I suspect, it may possibly be builder error.

Regardless, maybe my being a guinea pig will help keep their customers happy.

(Maybe, they'll feed me a steak too???):D

Ironflight
12-19-2008, 10:10 PM
Regardless, maybe my being a guinea pig will help keep their customers happy.

(Maybe, they'll feed me a steak too???):D

More likely some lettuce leaves.....:p

Pilottonny
12-20-2008, 04:11 AM
......than you think! Because I want to keep the passenger stick removable, I installed a separate PTT button on the panel, for the passenger. So if the passenger transmits, it may wel be that nobody has his/her hands on the stick, contrary to what some of you are suggesting!

Anyway, I spend more than $ 5.000,- on the AP and it has to work properly!

Regards, Tonny.

L.Adamson
12-20-2008, 06:59 AM
......than you think! Because I want to keep the passenger stick removable, I installed a separate PTT button on the panel, for the passenger. So if the passenger transmits, it may wel be that nobody has his/her hands on the stick, contrary to what some of you are suggesting!


My co-pilot/passenger PTT is on the panel, and it's no problem.....................so there is light at the end of the tunnel! :)

L.Adamson --- RV6A

Pilottonny
12-20-2008, 07:28 AM
Hello everybody,

"Andyrv", in a personal message, suggested that I tuck away the coiled up cables that are usually hanging out of the fuselage during construction (wings and tail not on yet). So I packed all these wires in aluminum foil and gues what? Right! problem almost solved! The pitch up is now minimised to one or two notches of the step motor, as where before it was going trrrrrrrrrrr......., all the way back. I can determine now that it even makes a difference where I am standing outside the plane, or when I sit inside.

Then after some more testing, trying some different frequencies, the problem was completely back, exactly as before. How could this be? (the problem is more severe in the mid range frequencies than at 118,00 or 136,00). I suddenly realised that I had hooked up the battery charger, that is sitting under the fuselage, because the battery voltage was dropping during testing. When I Disconnected the Pos. wire from the Battery: problem gone again! (almost). So all the wiring (not just the AP wiring) is picking up interference from the Antenna and passing it on to the AP Unit.

So the problem is definately comming from the radiating antenna, outside the plane, rather than from inside? There is still something to be fixed by Trutrak since 1 or 2 notches of stick movement still means there is something wrong. Also there is people already flying that have the problem (no wires hanging out of the fuse I guess).

A few more things I found during this extensive testing:
- When the unit is turned on for an hour or so, the stepper motor gets warm, not extremely hot, but stll warm, is this normal?.
- The horizontal LEDS's from the left display digit, keep blinking up and down, when the AP is engaged. What does this mean?

Regards, Tonny.

Sam Buchanan
12-20-2008, 11:10 AM
Hello everybody,

"Andyrv", in a personal message, suggested that I tuck away the coiled up cables that are usually hanging out of the fuselage during construction (wings and tail not on yet). So I packed all these wires in aluminum foil and gues what? Right! problem almost solved! The pitch up is now minimised to one or two notches of the step motor, as where before it was going trrrrrrrrrrr......., all the way back. I can determine now that it even makes a different where I am standing outside the plane, or when I sit inside.


Tony, as someone who has spent some time sorting out autopilots in RV's, may I suggest that you delay spending any more time fixing your autopilot until the plane is actually flying. As you have discovered, glitches that may appear in the shop may have no relevance once the plane is completely buttoned up and flying. I have seen "problems" with an autopilot disappear once the aircraft is out of the hangar, in the air, and subjected to normal aero loading.

You will have plenty of time to sort through any AP squawks once you begin test flights. It is my opinion that to declare "autopilot problems" while the plane is still under construction is most likely premature.

Best wishes for a speedy completion of your project!

SteinAir
12-20-2008, 12:21 PM
WAIT-WAIT-WAIT! We have 4 pages of discussion since your post, people spending time trying to troubleshoot your problem (TruTrak and me both spent our valuable time) and the plane isn't even assembled?!?!!? You have wires hanging out, etc..? I did miss the fact that your plane wasn't flying and that changes everything.

I better quit typing and bite my tongue because I'll say something inflammatory for sure.

PLEASE don't do any more "troubleshooting" on your avionics until you at least get the plane assembled and in the air. You can't possibly troubleshoot how the thing is going to act in the air whilst it's un-assembled in a garage/hangar. It needs to be in the air to know how it acts in the air.

It's far to difficult to even determine if you have a problem or not while the airplane is disassembled and not flying. You may or may not, but wait until she's flyin before you decide.

Stein

Mike S
12-20-2008, 12:49 PM
- What to do/test next?
- My plane is still in the garage (concrete floor with some rebar in it), could the signal be bouncing off the floor, causing this?
- Should the whip of the antenna be ?connected? with the center conductor of the coax? I do not get a reading on my ohm-meter when testing between the whip and the center conductor.


Regards, Tonny.

Looks like everyone missed this--------I know I did.

N8RV
12-20-2008, 04:08 PM
Wise decision, Obi-wan Steinobi. No sense starting an international incident over it. :p

As an aside, I did a little more fiddling today with my AP. And, yes, it's still in the hangar. And the wings are off now. And I have wired dangling out both sides.

I found that, when the alt hold is NOT engaged, keying the mike seems to have NO effect on the AP on any freq that I tried. However, as soon as I engage the alt hold, it starts going wonky when I hit the PTT.

However, since I now have to turn my attention to sanding and priming and sanding and priming and sanding and priming and painting ... I'm not gonna worry about my AP.

Just thought I'd finish my part of the story. Carry on ...:)

SteinAir
12-20-2008, 04:56 PM
Just a note to everyone who is testing transmissions and PTT's. When done inside a building or hangar or garage, you're likely to get all sorts of wonky things that won't happen in the air. It gets worse if you have random wires that aren't yet terminated hanging around your plane. It's ok to test things, but not necessarily a great idea to start transmitting in your garage/hangar until all the wiring is hooked up. Transponders too!

Cheers,
Stein

andyrv
12-20-2008, 05:08 PM
This interference applies to EFIS issues as well. I wasted 3 days of my time but probably only 15 minutes of GRTs time before my wings were on. I had 15 feet of nav/strobe/landing light and antenna coax on the outside of both sides of the fuselage. Because other people were reporting slight interference problems with their EFIS I kept troubleshooting. It was the coils of wires bringing the RF back into the airplane. Moving the wires greatly minimized the problem but I was still concerned.

When the wings were on and all wires terminated all the "problems" were gone!

Andy

sharpdoug
12-21-2008, 07:22 AM
I had a I-AP, authorized to install a pictorial pilot II in an RV-6. This replaced an existing S-TEC and Altrak. No problems with S-TEC or the Altrak. The first flight to Oshkosh became a pitch nightmare with Pictorial pilot II. The plane went back to the AP's shop for months, no change, hit the PTT and the pitch jumped up. Tried new auto pilot head N/C from Trutrak, new antenna, new radio, connected radio directly to battery, moved harnesses, checked as many shielded wires as possible, new coax RG 400, rerouted it, checked with hand held in the plane and outside of the plane, the problems continued. Moving the antenna seemed to help but not completely.
My final solution, which worked into my long term plans anyway, was to rip out EVERY wire, line, harness, and instrument. I bought the upgrade Digiflight II VSVG along with a full AFS glass panel, so if the problem exists after my total rebuild, I will try another hobby.
Some +'s out of all this frustration is that I have gotten to know some of the smartest and most patient people in aviation. The solution of moving the antenna sounded silly to me but disrupting the line of sight from the antenna to the radio might help. There is a solution and I disagree that you should fix this after the plane is built and flying. Try to get it right on the ground with the plane open because it is easier work on and moving antennas, wires, and cables now, is less work. My 2 cents. Good luck.

Pilottonny
12-21-2008, 10:47 AM
Stein,

I am sorry you misunderstood, but my question was actually (my first post in this thread) if this problem could be, because the plane was still in the garage! As a matter of fact, in several posts I commented thad I wanted to get this problem out of the way, before I closed up the front deck, because if anything (wirewise) had to be changed, now would be the time. As you will know, ones the plane is flying, rerouting the wiring is ten times more difficult.

Trutrak are aware of this, apart from this thread ,there was a lot of additional communication with Lucas.

Thanks for you replies anyway.

Regards, Tonny

SteinAir
12-21-2008, 05:55 PM
Hi Tonny,

I now understand your predicament and your desire to ensure that everything works well before you fly. That being said, some things just cannot be accurately tested before the plane flies. The best you can do is take the steps necessary to avoid possible "issues" once the plane is done. Sometimes issues can and do arise, and indeed you are correct that it's difficult to re-route wiring.

The above being said, I hope you can understand what I am saying as well. Spending many hours with yourself and the mfgr and/or dealer such as myself is a tremendous burden on business when we're trying to troubleshoot things with so many variables. Having the airplane unfinished and not assembled makes that job almost impossible....so the fact of the matter is at this point you're spinning your wheels to some extent. That translates into lots of hours, heartache and money spent not just for you, but for everyone involved.

I'm not trying to slam you, just letting you know that at this point the troubleshooting you're doing is likely much in vain because while gross problems may show up at this point, it's fairly likely you cannot replicate the conditions experienced in the air with the plane sitting unfinished in a hangar/garage.

Again, if you do as much prevention as you can in the beginning the end result should be a good plane overall. But, as with everything issues can and do arise. Two weeks ago we spent the better part of a day troubleshooting and RV8 with an AP issue that was extraordinarly difficult to pin down by TruTrak and us. Turns out a bent pin in a connector for the transponder was causing the problems. Tomorrow we have an RV-10 flying in with some weird remote magnetometer gremlins to try and troubleshoot. So, I'm afraid that occasionally despite your best intent and attention, things can and do happen.

The best advice I can give you and everyone else at this point of your build is to focus on doing things properly, using best practices and get the plane done/flying....don't spend time trying to find solutions to problems that may or may not exist. Things work out more often than not! :)

Have a great week and keep moving forward. Obviously you are a skilled builder who wants to have a nice plane.

Cheers,
Stein

mannanj
12-21-2008, 06:05 PM
Excellent reply Stein.

Your patience with people like me is remarkable. This shows why you have an outstanding reputation in the business and why people keep returning to you for repeat business.

breister
03-14-2009, 10:52 AM
Guys & Gals,

One of the regulars on the Lancair Mailing List posted this, and it may cure the problem (Caveat Emptor).


I am happy to report that the RF problem I was having with the Trutrak autopilot has been solved. One of the posted suggestions pointed to a filter adapter that is installed between the controller and the harness. I ordered part number FCE17-B25AD-250 from Digikey (http://parts.digikey.com/1/parts/1599616-filter-male-female-adpt-25pos-fce17-b25ad-250.html) for about $25 and it cured my system. Not a hint of interference from either radio.
thanks to all who wrote in.

Chris Zavatson
N91CZ
L360std
www.N91CZ.com

I haven't experienced the problem in my current plane, but if others want to try this and either confirm or deny the fix, I'm sure others would appreciate the feedback.

Oh, and there is now a TruTrak Forum here (http://trutrakap.com/forum/index.php).

N737Z
03-20-2009, 11:19 PM
I also have found TT and Stein to be very helpful, willing, and knowledgeable, but I have not been able to cure this problem in my setup. I also have the Garmin sl40 with the bent whip antenna and have tried many things with no success. I would be very interested in the success of installing the filter block between the harness and ADI head.

With unlimited variables in installations, I'm sure this is extremely hard to pin down, but I will eventually find the gremlins.

On another note...my unit will only use about 10 degrees of bank when turning. Is there an adjustment to steepen the bank with an ADI pilot II that has GPS input? 10 degrees will not cut it with ATC.

Cheers and thanks to all for the posts on this challenge.
Don in PHX

N737Z
04-02-2009, 12:16 PM
I followed the link as previously posted on the filter made by Digi-Key, purchased it, installed it in 5 mins, and it solved my pitch up problem with my PTT. I believe my problem originated with my using a single shield coax instead of a double shielded coax like RG400 on my radio antenna. I did route my coax originally completely separate from all other wiring, but apparently the Garmin puts out a lot of RF. Here is the link and the part cost $27 plus shipping. Good luck! :D

http://parts.digikey.com/1/parts/1599616-filter-male-female-adpt-25pos-fce17-b25ad-250.html

Don
RV7
PHX

breister
04-03-2009, 07:06 AM
Thanks for the additional confirmation Don!

I tried it too, and noticed a difference. This info is now posted on the TruTrak forum, and I urge anyone who has tried this solution to report their results in this thread (http://trutrakap.com/forum/showthread.php?t=43) on the TruTrak forum.

jay.pearlman
04-02-2010, 10:31 PM
I installed the Vans MP in a tube and fabric plane with the sensor box behind the panel. The MP would go full scale on transmitting. I moved the box only a few inches and the problem went away (mostly). Here the wiring bundles were not an issue.