COM antenna

[Kai]

This topic might have come up previously.

In the Sonex #0525 construction drawings it is suggested hat the base of the COM antenna is secured to the right rear corner of the glareshield, and that the antenna itself follows the windshield bow.

Has anybody actually tried this position? Results? Pros and cons?

If yes, what make and type of radio did you use?

Personally I am sceptical to any recaptacle close to the engine ignition system- but what do I know!

Any comments welcomed.

Thanks
Kai

[Friesen5]

I made the antennas outlined in the plans. My first radio, a Microair 760 and my present radio, a Flightline 760A both work fine. There’s a bit of a ticking noise, but not to the point of illegible reception. I designed the electrical installation with care. The shielded mag wires come through the firewall on the left side, while all other electrical connections come through on the right side. I have a grounding buss on both the engine side and inside the airplane. I covered the antenna wire (welding wire/rod) with a long piece of shrink tube. My Sonex has been flying since 2007.

Mervin Friesen
Sonex C-FMNX

[GraemeSmith]

I would hazard a lot of the signal is "lost" in the adjacent windshield bow.

[bvolcko38]

I built my first antenna exactly as per the plans. It was subject to noise and it was quite directional. SWR could not be tuned dry well either. After much frustration, I bought an antenna from MGL. Noise gone, reception and transmission is perfect, SWR is near perfect.

[9GT]

I have never been a fan of roll your own antennas. This guys antennas are high quality, reasonably priced, and work as they should.
http://www.deltapopaviation.com/Home.html

[Rick524]

An antenna for the com band should be mounted in a place with no obstructions around it
and a metal ground plane under it, at the feed point. On a Sonex that would be on top of the turtle deck. Mine works
perfectly like this with zero ignition noise and very good range.

Rick
C-GRIX

[mike.smith]

An antenna for the com band should be mounted in a place with no obstructions around it
and a metal ground plane under it, at the feed point. On a Sonex that would be on top of the turtle deck. Mine works
perfectly like this with zero ignition noise and very good range.

Rick
C-GRIX

Me, too.

[Kai]

Thaks, everybody, for your comments.

I’ll take this one step further and would like to know about your COM radio’s sensitivity to rfi. In Sonex #0525 I have an old Icom 200 fed directly from the battery (yes, forget to switch off after flight and the battery is down the next day). An RG58 runs to the simple rod antenna on the turtledeck. The Jab engine ignition with shielded p-wires to the switch and the common alternator/rectifier take care of rfi emission. This intallation gives no cause for rejoice!!

So,

What make and type of COM radio do you have installed? What make and type of antenna? Wire RG58 or RG400?

How is it fed with power? Directly from the master relay?, a separate avionics bus, hard wired directly to the battery? Or?

Just as important is the rfi emittor: AeroVee, ‘Other’ (VW aeroderivative), Jabiru, Covair, Rotax, anything else?

And finally- how well is the installation functioning; especially concerning rfi suppression?

Again- much obliged!

Kai

[WesRagle]

Hi Kai,

I had an icom-A200 in my old Sonex.



I had a whip antenna on the bottom of the airplane. None the less, I had problems with ignition noise. The details are a little foggy now, but somehow I discovered that there was an adjustment that could be made to squelch the noise. The adjustment is on the back of the radio. You have to slide the radio out of the tray to access it. After fiddling with that a little the radio worked great.

Wes

[builderflyer]

An antenna for the com band should be mounted in a place with no obstructions around it
and a metal ground plane under it, at the feed point. On a Sonex that would be on top of the turtle deck. Mine works
perfectly like this with zero ignition noise and very good range.

Rick
C-GRIX

Given that we operate our airplanes in 3 dimensions, there really is no such place. While operating on the ground there is a lot to be said for a comm antenna mounted on the top of the turtle deck. However, when we are in the air there is a lot to be said for a comm antenna mounted on the belly. On my Sonex, the comm antenna is mounted on the belly and in years of operating at a controlled airport, ground control or the tower never failed to hear my transmissions, regardless of where I was positioned on the field or in the air. So with the consideration of "looks" in mind, the belly wins hands down.

Just my opinion,

Art,,,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,,,Jabiru 3300 #261