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27k ohm or 39

Posted: Fri Feb 23, 2018 4:03 pm
by N333M
Working on my EIS 4000 install on 0-320 lyc , standard mags.
Plan is to wire p-leads to tach 1 and tach 2 inputs. Notice both 27k ohm resistors and 39k in package. Instructions mention both, no explanation as to how or why to choose which.
Hmmm. Any help appreciated.
Don

Re: 27k ohm or 39

Posted: Tue Feb 27, 2018 1:01 am
by jnewsum1
The words in the EIS User Manual (Rev L) only mention installing a 27K Ohm resistor between the instrument and the mag P-lead.

I found the info quoted below in the Dynon Skyview install manual about what value resistor to use with the Dynon EMS which might help explain why GRT ships both resistor values in their install kit.

" Six-cylinder Lycoming engines sometimes need more inline resistance to prevent false readings by the EMS. If you supply your own resistors, they need not be exactly 30 kΩ.
Additionally, both 1/4W and 1/2W resistors are acceptable to use. "

I would install the 27K Ohm resistor and keep the 39K in reserve just in case you have an issue with the tach signal later on.

Re: 27k ohm or 39

Posted: Wed Feb 28, 2018 1:46 pm
by N333M
thanks Newsum!