Instructions on hooking up RPM Sender

[Lsaircraft]

Hey guys I am getting ready to hook up my older MGL Stratomaster Ultra and wondering how to hook up the RPM On the Jabiru 2200 I have contacted MGL and they said just tap into one of the alternator leads Does any body have instructions on how to do this,

[ldmill]

I've got the same hookup - the older Ultra Horizon XL with RDAC X and a Jab3300. You just hook the wire from the RDAC rev counter to one of the two pale blue alternator inputs into the regulator. Very easy. You then have to tell the Ultra the calibration settings for the rev counter- how many pulses per 10 revolutions. I don't know for sure what it is for the Jab2200, but think it may be 5 pulses per 10 revolutions.

Highly suggest you download the online manuals for both the instrument and the RDAC to help in this if you haven't already.
Lorin Miller

[peter anson]

This has come up before. See http://www.sonexbuilders.net/viewtopic.php?f=8&t=2719
You can run the tacho off the alternator but some people have found that unreliable. The MGL instructions for the RDAC suggest using the same connection as for a Bendix magneto - connect from the low tension side of one of the coils to the RDAC tacho input via a 10K resistor and remove the ballast resistor link. I actually used a 12K resistor, presumably because that was what I had available at the time. It works perfectly, completely reliable. I have checked it against an optical tacho and it is accurate to the resolution of the optical tacho. Number of pulses per 10 revs would be set at 20 for the 4 cylinder or 30 for the 6 cylinder.

Peter
Sonex 894
275 hours

[vwglenn]

Like they said, the hook up is simple. Just run a lone wire form and alternator lead to the pickup point on the RDAC. Then set up your unit to count the pulses from the ignition. If memory serves it's 3 pulses for the 3300 and 2 for the 2200? Better check that though.

The resistor method worked for about 4 hours for me. Then it quit on my way to OSH this year. For some reason the RPM would ground out my MAG with the dipswitch in a given position. The alternator method never worked for me and is a pretty common problem. My RPMs would fluctuate wildly and I would get crazy readings like nearly 3400RPM on climb.

I've given up and purchased the Camit Tach sensor. Hopefully completely isolating the RPM pickup will fix the issue. Hope to have it installed this week.

[sonex1374]

Although not applicable to the MGL setup this helps round out the discussion.

I use a Dynon Skyview EMS and run the tach wire to one of the alternator pigtail wires. I placed a 10k ohm resister in-line between the EMS unit and the pigtail connection to stabilize the RMP reading. This setup has worked flawlessly. As with other systems you'll need to go into the EMS programming and set the pulses per rev setting, based on your particular engine. The Dynon defaults to a 4 cyl engine pulse setting and I initially overlooked updating that for my 6 cyl Jabiru. I was fairly concerned for the first couple flights as to why my engine had a tendency to over-speed....

The Dynon works great!

Jeff

[kmacht]

I have an older stratomaster ultra. I picked up off of one of the alternator leads. Take a look at your rdac manual. I rember needing to add a diode between two pins on the old rdac that I have.

Keith
#554

[vwglenn]

Just an FYI. The Camit tach sensor cured my RPM issues. They're rock solid after three hours of fight time. Too flippin bad Camit appears to have shut down.