Dale Smith wrote:

Paul,

Ken Powell was nice enough to send me this link to the Kubota
dynamo.

 It is: http://home.hiwaay.net/~langford/corvair/dynamo.html

This looks like just the ticket for a backup unit or a drop
down RAT.

Dale Smith

This "dynamo" is from a John Deere model 670 lawn tractor (any X70, actually), and weighs 4 pounds with the regulator. Output is 20 amps minimum when driven by
the mower's 6" pulley running at 2500 rpm. Part numbers are AM877557 for the alternator ($160), and
AM101406 for the regulator ($67). The wonderful thing about
a dynamo is that it uses permanent magnets rather than field excited electromagnets, so it doesn't "need" electricity for the windings to produce electricity. I've added
up all of my electrical loads, and 20 amps will handle everything I have, including 8 amps of landing lights! Even without an alternator charging, my battery will last me
4 hours without even killing the radio or transponder. And my EIS (Engine Information System) will notify me if the system stops charging below a certain level. 

There is some concern that an alternator/regulator designed for a tractor might produce a lot of RFI noise that would interfere with NAV/COM radios. Troy Petteway's
expensive B&C alternator on his C-85 looks just like this one, and he has no problem at all with noise in his Bendix King radio. Also, the top electrical engineer at TBE
felt sure that as long as the regulator used solid state components (rather than the old breaker or vibrator type) that noise should not be a problem at all, and this one's
definitely solid state. But I should mention that I haven't proven this to be true, yet. 

I'd like to thank Chuck Corum of Farmer's Tractor Co, Huntsville, Alabama (256-830-4020) for spending several hours researching this application for me, and
making sure that the components matched, and providing me with copies of everything I'd need to install and troubleshoot the system for years to come. He didn't have
to do that. I owe him a few flights around the patch! And I'm probably lucky that it's a slow time of year for local cotton farmers too. 

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