David W wrote:

anyone have experience with a plugin(switch) for a handheld radio to go through the external antenna ie for a backup to a radio failure.  in the spirit of redudancy, i was thinking of adding this to my panel as early on i had a stuck mike(fixed with replacement of the audio panel) and i thought this may be a worthwhile backup.  however, upon looking further into this, apparently it may rob the panel mounted radios of db's and i have read that when it is used it may damage the panel mounted radios. fact or fiction?  is it worthwhile? downsides?



David,

Any time you run the antenna feed through a splitter, or a switch, you lose signal. The very best (read expensive) ones lose only a couple of db, but it's measurable. Less expensive ones can significantly affect your transmission/reception range. The general recommendation: Don't use one unless you have to do so. If I understand your need correctly...for an emergency backup (you have two "mounted" antennae and radios already), consider just using the handheld with the provided plug-in stick antenna if such an emergency occurs.

I have SL-30 and SL-40 comm radios in my IV-P. The -30 is tied to a belly-mounted whip antenna, and the -40 to an Archer antenna built into the tail per Lancair building recommendations. The tail antenna gives acceptable performance when talking to sites more than about 15 degrees off the nose, but is pretty well blanked for stations directly in front of the aircraft (AWOS/ATIS at the destination airport is a good example). The belly-mounted antenna gives somewhat better performance(range) than the tail antenna in all directions and doesn't have a blind sector on the nose.

I lost my SL-30 transmitter during cruise at FL 220 last year. Took a couple of minutes to figure this out, then switched to the SL-40 and called center. Worked fine...as expected. I advised the controller that I'd lost the primary radio and wanted to check out my ICOM handheld as a backup...I had never turned it on in flight. We estimated that I was about 60 miles from his transmitter. My transmission to him was weak but readable; his transmissions loud and clear to me. We thought that this was an acceptable emergency backup way to communicate if needed.

I continued on with the SL-40/tail antenna and had no further issues/problems. Pulled the SL-30 when I got home and Garmin fixed it under warranty; the local shop loaned me a sub to use while it was out... (BTW, these radios are "plug in" and easy to change; just might require some configuration.) I couldn't have been happier.  :-)

Bottom line: if you already have two panel-mounted radios, consider just using your hand held as a "last ditch" backup with the installed whip; very unlikely you'll ever have to use it, but in a pinch it's there... My guess is you'll have more of a problem keeping fresh batteries in it (I change mine during each condition inspection) Pleased to answer any questions.

Bob

PS: If you use an antenna splitter, rather than a switch, you can damage your panel radio by transmitting on the hand-held. I understand that some radios will protect from the signal overload, but for my money, it's not worth "home testing."