Van's Air Force
The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!
EGT Indications
- Thread starter Flavius
- Start date
And mine.
I had an RF problem with my MP sensor (on an SDS ECU for my Subaru engine). The ground was good, so I put 1000pf capacitors from each signal lead to ground and the problem was solved. I had tried snap on iron baluns on the wire first, and they helped, but the capacitors were a better solution for me.
I depends on weather your EGT probe is grounded or not grounded. Grounded probes have the thermocouple junction welded to the probe's outer sheath for faster response times, but can be more susceptible to noise and RF from ground loops. Ungrounded probes are insulated from the sheath, providing immunity from ground loop issues but with a slower response time. My ISSPRO 2-1/4 EGT (Vans Gauge) did the same thing, but my newer UMA EGT with ungrounded probes are "rock solid". Also, using double shielded coax to your VHF antenna should help.
rich
Well Known Member
I had the same problem with an older Skyview EMS. Called Dynon, said older they had problems in some of the older models.
Replace the EMS circuit board and fixed the problem.
johnpaul44
Well Known Member
had this exact problem, when the egt probes are not grounded they act as antennas and pick up the RF energy. My bet is loose or missing ground somewhere
Oddly enough, grounded probe systems are more suspectable to ground-loops than purely differential style probes and meter input circuits because common mode noise and/or RF interference gets canceled in the instrument's input circuit itself (i.e. by the non-grounded differential op-amp input circuit, which only pass difference signals and rejects common mode signals and noise). I changed to a higher quality UMA non-grounded EGT probe and gauge and completely eliminated this issue.
Last edited:
