Com radio interfering with Enigma

[Rick524]

I have my Xcom and Enigma panel wired and in the Sonex. I found that when I transmit, my Enigma altimeter goes up or down 500 feet or so. My antenna is mounted on top of the aft fuselage, above the second former.
Anyone else have this problem?

Thanks!

[n982sx]

I have the same setup as you but have never had any problems.

I'm curious about what may be different. My Xcom radio is right next to the Enigma in the panel.

Did you install the chokes on the Enigma wiring? My antenna is also mounted a little further back than yours. It's just in front of the third former.

[Rick524]

Hi Bob, I only have the one supplied choke installed on the main Enigma power harness. That leaves the sp6, sp7, iox, audio out, backup batt, rdac and secured supply with no chokes. I'm going to order
chokes to install on these lines.
I can pick up emi from the Enigma with an aviation portable from a foot away. I made a shield that fits around the top and bottom of the Enigma to try and block the radiated noise. It helped a bit, but didn't eliminate it completely.
I'm surprized that others don't have this problem. Maybe the chokes are the answer.

Rick
Sonex 524

[n982sx]

I don't remember what lines I have the chokes on, but it was on more than just the main power harness. I thought I received several from MGL with the Enigma.

I was just flying today and the Xcom and Enigma work very nicely together. I almost never set the frequency directly on the Xcom. I mostly just hit the flip flop or adjust squelch. Once you get your issue resolved you'll enjoy both pieces of hardware.

[Rick524]

Just an update. I disconnected all but the + and - 12V lines to the Enigma. I can transmit with no change in altitude showing on the Enigma, and no increase in received noise on the x-com. Then I connected the - side of the backup battery wire, without the backup battery connected to the other end. The altitude changes when I tx and the received noise increases on the x-com! This is just
a 10" piece of wire hanging on the - backup batt post. I guess its acting as an antenna, feeding rf
into and out of the Enigma. I get the same result when I connect anything to the Enigma inputs. I had some small ferrite beads in my junk box, so I wired them in series with the backup batt lines. Tried transmitting this way and see no interference on the altimeter and hear no increase in noise on the x-com.
It looks like I need chokes on every input and output on the Enigma. The good thing is I don't have
the glare shield on yet and its easy to do.

Rick
Sonex 524

[n982sx]

Nice detective work Rick. Looks like you will be able to be interference free.