Amp meter goes off scale when radio is keyed

[tommyturner]

First noticed the problem as the amp indication rising to as high as 60 to 80 amp while transmitting on #1 com. #2 com was fine. Swapped the antennas on the back of the radios and the problem shifted to the #2 com. Rerouted the antenna cable to be away from other wire bundles and now the amp indication goes to zero and shows a red X when transmitting. Any ideas?
The amp shunt is in series with the Alt lead. System is dual SV and the antenna cable is RG400. The voltage reading only varies between 13.9 to 14.2 so I am pretty sure this is an indication error.

 

[Dynon]

This may or may not be an issue that affected a couple of EMS modules in the field. In any case, it's solvable via a 37 pin filter (that we can provide), or, we could either repair your module or swap you for a different one. Give our support team a call at 425-402-0433 or an email to support at dynonavionics dot com. Tell them to reference case 109912.

 

[JTD]

I just had my first flight after sending my EMS modgule to Dynon for the fix for jumpy CHT/EGT. EGT still jumps up like before and now amp meter does it to

Any ideas

 

[Dynon]

Tim - Our support team will be in touch with you directly to follow up (I think they may have gotten with you already).

 

[GHDZ]

This may or may not be an issue that affected a couple of EMS modules in the field. In any case, it's solvable via a 37 pin filter (that we can provide), or, we could either repair your module or swap you for a different one. Give our support team a call at 425-402-0433 or an email to support at dynonavionics dot com. Tell them to reference case 109912.

Will this "filter" also fix the same issue (temperatures go crazy when a radio transmits) with the EGT/CHT?   

 

[dynonsupport]

No, the external filter is only useful for Amps noise. To fix EGT/CHT we must see the EMS back at the factory.

 

[GalinHdz]

No, the external filter is only useful for Amps noise. To fix EGT/CHT we must see the EMS back at the factory.

RATS!!! That means I will have to wait until I take the airplane down for maintenance to correct this annoying issue. THANKS.  :'(

 

[tommyturner]

I received an EMS module from Dynon with the latest update and now radio transmissions do not affect any of the indications on the SV displays.

 

[swatson999]

I received an EMS module from Dynon with the latest update and now radio transmissions do not affect any of the indications on the SV displays.

I was thinking of sending in my EMS when I send the SV display in to get upgraded, but before I do...

All of my values look solid except EGT/CHT whenever I transmit...I see a change of a few degrees (maybe 3-5 degrees) on both sets. It's so small as to be effectively invisible in flight, but I see it in the data (usually an increase, sometimes a decrease).

Will the EMS "fix" that I read some stuff on fix this issue?

 

[Dynon]

The PTT affecting the CHTs and EGTs issue that you've read about usually results in pretty drastic spikes. It's possible that your EMS is not afflicted and you're still getting a little RF energy into the EMS module somehow. We'd still be happy to take a look at your EMS module though and see if it needs the mod. If you tell us you EMS's serial number, we can take a pretty good guess at whether your EMS might be affected by that issue.

 

[swatson999]

Serial #2170

 

[Dynon]

So that's old enough that it could be the issue that we can fix. If you want to send it back, give our support team a call at 425-402-0433 or an email at support at dynonavionics dot com to set up an RMA

 

[n97kd]

I reported a similar issue a few weeks back to Dynon Support.
My manifold pressure indication and my No.2 amps (hall effect) would peg out when either comm were transmitting.
Dynon suggested to check the coax or have a radio shop check for RF leaking. I haven't had access to the shop yet, but I did try shielding.
I wrapped some foil around the wires from the manifold pressure sensor and grounded it. It worked! it stopped all interference on the manifold pressure and there is just slight rise on the amp indication (1 amp).
My question to Dynon is: is the problem with my EMS module sensitity or noise rejection or just need shielding? I purchased the unit in the spring of 2013 so I don't know if it falls in with the unmodified units.

Thanks in advance

Don Yoakley
dual skyview install.

 

[dynonsupport]

Don,
We haven't made any changes to the manifold pressure input and don't generally have issues there. The changes to the EMS were for EGT and CHT radio interference.

That sounds like a LOT of RF energy is getting into your MAP sensor or one of the 3 wires. I'm not sure what to say- that's a very uncommon issue, so I don't quite know what else to tell you. If you have two radios and both do it, it's much more likely the MAP sensor or MAP wiring since it's unlikely you have two bad radio cables.

What kind of plane is this, and what kind of COM antennas do you have?

 

[n97kd]

My plane is a Glasair III with internal di-pole foil antenna, one in the vertical stab and one just behind the seat back.
I believe the coax is RG 400 or similar, that Glasair provided with the kit.
I am in communication with tech support on my private email and considering an RMA because I now have another issue of one channel EGT pegging out with a red X, (not related to comm TX). It's not the probe because with it completely disconnected I can induce the full scale reading by just putting my hand close to the red wire near the blade connector. Very strange.

 

[jakej]

Don
Composite & static electricity come to mind here

Also, did you do a SWR check on you antenna ?

Pm me if you want - I may be able to give some info of use to you.

Jake J
Glasair IIS
Avionics installer & without any RF energy issues with now fitted dual Dynon systems

 

[dynonsupport]

The EGT pegging out sure sounds like a probe or crimp to me. The reading going full scale when you put your hand near it is 100% normal and expected. The voltage out of an EGT is only 0.040V, and your hand near a wire can easily create that. With a bad probe or crimp, all bets are off with what a thermocouple will read.

We have a Glasair Sportsman with the same antennas in the same places with zero issues, so it can be done. Is your MAP inside the cabin or firewall forward?

 

[n97kd]

I finally determined the bad EGT reading was an intermittent probe. I have one on order to replace it. I had Dynon send me a replacement EMS and it did the same thing but even worse. With everything hooked up all the CHT and EGT readings went to full scale. The unit was a remanufactured unit I suspect it may not have been fixed. I sent it back and reinstalled my original EMS. Now that I know that he EGT sensor is such low voltage that explains the issue of my hand inducing enough energy to make the gauge move.

Back to my MP pressure and comm tx issue. I checked both of my coax cables (double shielded) and they are physically intact (no shorts or opens). Swapped them with no difference. My SWR readings on both comms are around 3.0 at mid frequency 127.0, 1.5 on 118.00 and 3.1 on 136.00. I adjusted the coax length to achieve the lowest SWR. Both my EMS unit and the remanufactured one would see interference (MP move to full scale when transmitting on either comm). Interestingly the worst interference is at  the lower end of the frequency band starting at 118.0 and minimal at 136.0.

I saw an earlier post that Dynon has a 37 pin filter. Is it still available and would it help?

Also, are there any other Glasair (fiberglass) builders out there with similar issue?

Thanks

 

[Roger_Lee]

Dynon,

Will this 37 pin filter dampen the up and down amp readings with a Rotax engine?

 

[Dynon]

Don - are they go full scale only when transmitting? Or anytime it's on?

Roger - No, the amps readings won't be damped by a 37 pin filter. Are you seeing this on SkyView or a D10/D100 series product? The generators on Rotax engines are a bit noisy, and amps fluctuations aren't completely unexpected (particularly on the D10/D100 series, which doesn't have a high enough sample rate to damp the fluctuations as well as SkyView can)