EMS spikes etc

[jakej]

RV6-KPTW

"(15 hours or more since upgrade to latest software) since install of new panel, "

In your case then I'd suggest that after 15 hours it is not software related, more likely to do with the install of new panel.  What airframe type do you have ?

Jake J

 

[RV6-KPTW]

Jake j - I fly a 1995 RV6 with ~1900 hours on the airframe.

  So the reason I jumped in was i think i bring new info to the topic.  In my case i have 89 hours on system, and 15 hours since upgrade - a stable system in other words. 

I have a Dynon 10 and a 7 installed and the 10 had some kind of hiccup on startup for the flight when I noticed the problem - peculiar vertical lines and seemed to reboot - the 7 beat the 10 to flight display by a significant period of time ~20 seconds or so.  Very unusual behavior.

So I am left to wonder if this reboot is a symptom of an internal Dynon unit issue or coincidental. 

Back to the ems spike - Could be rg58 vs 204 but unlikely given the history of the plane - seems to me as it is narrowed down possible to a physical cable issue - loose connection, crimp, etc... I will work on that and report back.

Thanks

 

[jakej]

The joys of troubleshooting  :-? - mechancal breaks are easy to fix but those nasty invisible electron critters are an entirely different ball game, what works in one situation can be totally different even if you change things slightly.

For example - I wired 2 RV7's with identical electrical systems, #1 worked perfectly from day 1 but #2 kept popping the Alt field breaker each flight and, oddly,  sometimes when using the PTT. 

After much head banging, research (no one had an answer)  & systems checking, the solution was to fit a shielded wire from the alternator field terminal to the field terminal on the bus system.  Go figure !!

Just trying to point out here that the resolution of an 'issue' can be simple HOWEVER getting there can be very difficult, even for the 'experts' - persistence will pay off eventually.

Jake J

 

[mmarien]

RV6-KPTW

Could have been happening all the time as it not unusual to NOT be paying attention to gauges while communicating. I remember it happening to my analog gauges three years ago, but never noticed it on the Skyview upgrade until the topic came up on this forum. Don't know where I was looking before? :

On this topic, my fuel gauge goes down rather than up. Almost told tower I was out of fuel and returning to field on departure. :-?

 

[ggerhardt]

Just another case to add to this issue.  I did my first engine startup today.  Rebuilt the engine (IO-360) so I had to do the Lycoming break in which involves running it for 15min.  I had nothing better to do than look at the engine monitor.  I tested the PTT and did see a little blip in the EGT/CGT, maybe a couple degrees.  But every 2 min or so, I would see a rather major increase in all EGT/CHT values that would last a couple seconds.  I didn't initially appreciate that it was happening regularly until about the 12min mark of the engine break in.  I couldn't think what might be causing this, but then I remembered that I turned on my APRS system to test it (http://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System) - it broadcasts about that frequency.  I wasn't able to completely correlate the APRS packet burst with the CHT/EGT rise, but I'm pretty sure that's what was doing it. I'll check it again tomorrow and make sure its happening when the APRS is broadcasting its data burst.

Geoff
Velocity 173RG

 

[ggerhardt]

Confirmed at the hangar today that the regular ~1sec pulses in CHT/EGT were from my APRS sending out its periodic data packets. Both the APRS and PTT give a steady 10deg F increase in all 4 EGTs. In CHTs, the response to the PTT/APRS is 10,8,4,2deg F for cyls 1,2,3,4 respectively.

Geoff
Velocity 173RG

 

[PeterBain]

Surfboy - no damage is being done when you see the spikes - It's only the reading which is erroneous. Thermocouples are sensitive to very small amounts of signal, so even small amounts of noise can have a drastic looking effect. We're working hard have a fix available.

Just returned from a trip around africa and those spikes really starting to freak me out as everything goes red when you transmit.Any update on a fix

 

[preid]

Call Dynon they have a fix for this. It's hardware based. I have not seen a spike since the replacement.

 

[Dynon]

Sorry we missed this thread. If you're seeing CHTs/EGTs spike on radio transmit, get in touch with our support staff at 425-402-0433 or support at dynonavionics.com

 

[PeterBain]

Sorry we missed this thread. If you're seeing CHTs/EGTs spike on radio transmit, get in touch with our support staff at 425-402-0433 or support at dynonavionics.com

Hi i live in South Africa so difficult to phone US
Please advise what i should be doing to rectify this problem?
Does it mean sending the unit back to the US or is there a local fix?
Please advise as my problem is particularly bad with all in the extreme red when i transmit

 

[Dynon]

Ultimately, we will need to get your EMS module back here. Emailing support@ will work - our support staff can get the return authorization going that way.

 

[alpinestar]

Sounds like there is a known hardware issue with some of the EMS units... I am finishing (at last!) my skyview install with EMS unit S/N 2257. Now would be the time to send it in for modifications if needed... Is my S/N affected?

 

[Dynon]

It's very rarely seen. Though newer EMS units have improvements to combat this, most installations with an EMS module of any vintage don't see this issue. It's not really a hardware "defect", per se. But we realized that we could make the EMS modules less susseptible to RF/EMI interference in installations that were less than ideal from an interference standpoint. Placement of antennas, coax, EMS modules, and radios can all influence this issue.

 

[bruceh]

It's very rarely seen. Though newer EMS units have improvements to combat this, most installations with an EMS module of any vintage don't see this issue. It's not really a hardware "defect", per se. But we realized that we could make the EMS modules less susseptible to RF/EMI interference in installations that were less than ideal from an interference standpoint. Placement of antennas, coax, EMS modules, and radios can all influence this issue.

Is there a S/N range for the potentially affected EMS units? My EGT's/CHT's spike when trying to transmit on the Dynon COMM radio.

Here is some example data from a recent taxi test.

 

[dynonsupport]

I don't have the serial number list in front of me, but all modules sold up until the end of 2012 have the potential to have this issue. It is based on the install, not the EMS module, and it wasn't a defect in a batch of units or anything. It took us years to find since it effects a very small percentage of installs, probably less than 1%. For whatever reason, some planes expose the EGT/CHT wiring to much stronger RF than others.

If your install is doing it, then you pretty much are guaranteed to have a unit that doesn't have the improvement. Once we found the root cause, the issue was pretty clear and the fix was well understood so it works in all cases we know of. We have yet to hear of an improved unit doing it.

We're happy to fix that unit any time you can afford to send it to us for a few days.

 

[bruceh]

I definitely have a pre-2012 EMS unit. I will get it back to you. I'm just now trying to finish up my build and get it all sorted as best I can prior to first flight.

Has anyone had this RF interference affect the ability to transmit on the Dynon COM radio? My COM works great on receive, but transmitting has been intermittent. Sometimes I can be heard and sometimes it is choppy or non-existant. Running the engine seems to make it worse, but not always. COM antenna is on the belly under the passenger seat pan (RV-9A), EMS is up by the firewall on the opposite side. Continuity has been checked on all of the wiring and the antenna coax is nowhere near the EMS. I've heard that the auto plugs on the P-mags may be the problem, so I'm going to fiddle with those before I send back the EMS unit.

 

[jakej]

Bruce

I think the auto plugs idea is a red herring I've been running dual p-mags in a Glasair for (composite airframes can sometimes be problematic with EMI/RF ) 70 + hrs without any problems, however I also haven't installed my dual dynons yet.

Jake J

 

[swatson999]

Just a question...now that I look really closely at my data, I see small spikes every so often...maybe 5-10 degrees in EGT, 3-4 degrees in CHT...every so often. I can't positively correlate them with radio transmissions, but it seems possible (they're pretty infrequent on any given flight, but seem to correlate with when one would be making transmissions, such as t/o, ldg, sector handoffs, etc.).

So my question is...how "clean" can one get these data, anyway? I'm not in any hurry to chase down such a nitpicky issue, a few degrees of spike here and there doesn't bother me, and I'm for sure not messing with my wiring harness over it. But it might be convenient during painting to send the EMS in for upgrade *if* it's even possible to get *all* the spikes out of a typical GA system like this.

If this is "about average", then to heck with it .

Ideas? Experiences?

TIA!

Steve

 

[dynonsupport]

It's good you brought up the issues with your radio as well. I think these two issues are very much related.

The EMS has issues if too much energy gets into the CHT/EGT wiring. Generally, this has been an issue on composite airplanes where the airframe doesn't block RF from the internal wiring.

In your case, you are getting this on a metal airplane, but you are also having transmit issues. This sounds a lot to me like the radio is transmitting a lot of its energy inside the plane, not outside like it should.

I really think you have an issue with your antenna or antenna wiring. Simple continuity checks aren't always enough with RF. Bad crimps, cables that have been crushed, or ground connections on only one end can cause big problems.

The easiest way to check this is with a VSWR meter, which an avionics shop should have. You may want to swing by one and get your antenna and cable checked. This measures the amount of energy that goes out the antenna vs. getting reflected back. Bad connections cause huge reflections.

Right now, you kind of have a virtual VSWR meter in the plane- your EMS! I assume you get the EGT/CHT rise on the ground, so you might want to play with your antenna cabling and see if changes help the EGT/CHT rise. I bet if you solve that issue, your transmissions will get better. One thing to consider is just running a commercially made BNC cable temporarily from the radio to the antenna as a test on the ground, to see if your cable has an issue.

There's no immediately logical way that a noisy ignition system can mess with transmissions. Noise messes with your reception, not your transmission. However, bad VSWR is much worse for transmission than reception. Plus, the Dynon radio is an awesome receiver so even with a bad antenna it's still pretty good.

 

[dynonsupport]

Steve,
Correlate your EGT spikes with your ammeter if you are trying to see if it is RF transmissions. The 5-10A the COM draws should be pretty visible.