Cotton AeroVee 0795

[Bryan Cotton]

Peter,
Since I posted that two+ years ago, we rebuilt my '99 Saturn for Adam to drive to the local community college. We have since discovered more locktite. To put the gearbox back together we had to use the purple stuff and it was expensive. Which colors of the cheap stuff do you mix for purple? Blue and red?

[peter anson]

Gee, I didn't even know about the purple Loctite. Obviously red plus blue.
There is a small job on Jabiru engines that requires about 6 drops of hi temp Loctite, 620 I think (green). It only comes in large bottles and costs about $56 a pop. I have bought a couple of those and it breaks my Scottish ancestral heart to throw them out. A bit of a fib there; I use it for almost anything I think is not too important until I can't squeeze it out of the bottle, it really does have a limited shelf life.

Peter

[Bryan Cotton]

I think I've got the magnetron p lead issue. Check out the video at about 3:00.


I've got a note into Sonex tech support.

[Rynoth]

Referencing my post from several years ago about my bad mags:

viewtopic.php?f=7&t=2468

I did end up receiving replacement mags, which worked correctly. My problem was indeed bad mags.

Here are examples of tests I performed on the bad mags:

"I have run numerous tests on both of my magnetrons and cannot keep them from firing. I have grounded them to the engine block using wires from the mount bolts, with an additional wire to battery ground. I've tested the continuity of my DPST magneto switch and it conforms to the specs in all regards. As an additional test, I ran a temporary wire from the p-leads to engine ground and the engine still runs on primary ignition only."

Basically, make sure that the body of the mag has continuity to your p-lead grounding point. It's possible, though very unlikely, that your accessory plate (to which the mags are presumably screwed into and have continuity with) is not grounded. Eliminate any possibility of an open circuit between the p-lead and the body of the mag, and if the mags are still firing they are bad.

[Bryan Cotton]

Thanks Ryan! I remember that thread. In re-reading it, I will try directly grounding the magnetron P leads to see if they still work. Seems like a clever troubleshooting step that will be easy to implement.

I also remember this thread:
http://sonexbuilders.net/viewtopic.php? ... 33&p=44800

I did use shielded wires, as in this schematic:


Electrically I see it as the same as what is in the AeroVee manual:


Kerry was not keen on the shielded wire. Maybe that is not a fair statement, he wanted me to wire it exactly as shown in the AeroVee manual before we declared the shielded wire innocent. That is reasonable. But before I run new wires through the firewall I'm going to just short them out directly and eliminate the switch.

Also I did ground the magnetron bodies. I put a lug under one of the mounting screws on each magnetron and ran that wire to my ground block at the starter. Before I did that, it ran poorly on the magnetrons only. After that I was able to get 3000+ RPM static on just the magnetrons.

I received my AeroVee either September or October of 2014, same date as the other problem children.

[Rynoth]

I received my AeroVee either September or October of 2014, same date as the other problem children.

Yup, mine was Nov 2014. Seems like a smoking gun.

[Rynoth]

Also I did ground the magnetron bodies. I put a lug under one of the mounting screws on each magnetron and ran that wire to my ground block at the starter. Before I did that, it ran poorly on the magnetrons only. After that I was able to get 3000+ RPM static on just the magnetrons.

Bryan, I'm sure you've done this already but figured it's worth mentioning... do you have a dedicated heavy-gauge ground wire from your starter to ground block? Otherwise your starter could be finding its ground path through those magnetron lug wires.

[Bryan Cotton]

Bryan, I'm sure you've done this already but figured it's worth mentioning... do you have a dedicated heavy-gauge ground wire from your starter to ground block? Otherwise your starter could be finding its ground path through those magnetron lug wires.

My ground block is mounted on the starter.


Edit: in another thread people were asking where to ground the engine case. Here is my ground, on the distributor hold down stud. This wire goes back to the ground block in the other picture.

It's not shown in the first picture, but later I had added ground wires from the magnetron bodies to that ground block under the starter mount bolt.

[Rynoth]

Ground setup looks great Bryan. If you run temporary p-lead wires to your grounding point and the mags are still firing, I can't imagine any other proof needed.

[Bryan Cotton]

Here is the harness I made. I cut the plastic off the female spade connectors so I could make sure they were installed properly. I twisted both pairs of 16ga wire into a 3/16" lug.

Here is the harness installed on the top. I added the nut I'm pointing to for the lug. The two wires are running across my other finger.

Here it is on the bottom magnetron.

Here is the video.


Still ran poorly. I swapped back and forth between front and rear EGTs. Neither one got as cold as I'd expect for a shut off mag. Runs horrible when the p lead is shorted, however.

After I shut down I had a thought, and did another run. Instead of shutting off the secondary with the switch, I pulled the main breaker. As expected, it behaved the same as shutting off the switch.