ROTEC radio noise

John,

I found your website and the MF3-A looks like what may do the trick on my experimental aircraft that utilizes a handheld ICOM A-21 aircraft radio.  The magneto on the Radial engine is putting out an RF signal that interfers with the radio.  It goes away when I ground the mag and operate off the electronic ignition (which replaces the 2nd mag). ROTEC people have no specific recomendations but I think you have the right product to solve this problem.  Am I correct in my assumption?  Is this the correct suppressor? The ROTEC uses a non descript magneto and is not a Bendix or Slick .  I would like to order one if you think it will help. 

The MF3-A is designed for certain Bendix magnetos - it may not work or it might make the magneto not work correctly in other applications. How about the rest of your ignition system? Are the leads and plugs shielded?

The all important ignition system utilises two auto type spark plugs per cylinder independently fired by both a single self-energized magneto and Hall-effect 12 volt electronic ignition system, virtually eliminating total ignition failure when used in tandem.  Timing is fixed at 22 degrees BTDC.

Shield the P lead wire. That is your first project.


Sounds like it is working as designed unless it is unique to your airplane. Possibly Rotec does not anticipate the use of radios in aircraft? I would push on them until I got to engineering to find out if this is a design feature or a defect. 

There is a reason why modern aircraft engine use metal jacked shielding on their ignition wires and large shielded spark plugs as long-range radio communication under all conditions is vital to air safety. The aircraft industry moved away from the Rotec design and "automotive' spark plugs in the 1940's. Unless the laws of physics have changed since then, the Rotec design is inexpensive but unfortunately rather old and obsolete.