M-16 Transponder Antenna Installation

[perbgyro]

Looking for pictures of Transponder antenna mounting in an M-16.
Wanting to mount in the nose and have a fiberglass body.
Thanks!

 

[schmoe90]

Here's a crop of mine from a picture I have on my phone - I can do better at the weekend if you need it Basically it's pretty much underneath the pilot. Remember you'll need some distance between that and any ADS-B antenna you mount (mine's under the fuel tank on the left hand side.)

 

[Tyger]

Mine is also in the underside of the nose, between the wheel and the landing light.

 

[PeterFromLA]

Make sure you plan to have 3 feet between the transponder antena and the ADS-B Out antena...when you decide to add the ADS-B Out...

 

[Tyger]

Um... the ADS-B Out antenna IS the transponder antenna, at least in my setup.

 

[WaspAir]

Mine, too, for "out". Separate GPS receiver antenna, of course.

 

[perbgyro]

Thanks everyone!

 

[PeterFromLA]

Um... the ADS-B Out antenna IS the transponder antenna, at least in my setup.

It depends what kind of transponder you have...

In my machine, I have a Mode C transponder with EchoUAT for the ADS-B Out. Both have their own antenas.

If you have a Mode S transponder, them maybe (not 100% sure here) you may have just one antena...

 

[schmoe90]

Um... the ADS-B Out antenna IS the transponder antenna, at least in my setup.

Lucky you My Funke apparently sends the wrong version of the ADS-B packet, so I need an EchoUAT (with its own antenna)

 

[PeterFromLA]

Lucky you My Funke apparently sends the wrong version of the ADS-B packet, so I need an EchoUAT (with its own antenna)

But with the EchoUAT you also get ADS-B In and a WIFI connection to your "portable" GPS or tablet...

 

[schmoe90]

But with the EchoUAT you also get ADS-B In and a WIFI connection to your "portable" GPS or tablet...

Or you would if you didn't have a Garmin that only supports their GDL39/5x devices

It does mean I have ADS-B In on my passenger tablet running Avare when I remember to charge it and bring it along

 

[Learjet]

I have found that the fin type antennas are much more robust and durable than the wire rod antennas - particularly as here in South Africa we are frequently using rough / bush strips with taller grass tufts which can snag it.
I ordered my fin antenna from https://www.deltapopaviation.com/Transponder_Antenna.html and it works perfectly with my Trig TT21 Mode S transponder. (I frequently fly in military / controlled airspace).
When installing the antenna make sure that you leave enough space for a square metal ground plane (120mm x 120mm) or a ground plane of 4 wires or rods radiating from the antenna base to a length of 1/4 the wavelength (68.8mm length). (refer to your specific Transponder manual for exact ground plane requirements).
Regards, Dave

 

[nomie]

I have found that the fin type antennas are much more robust and durable than the wire rod antennas - particularly as here in South Africa we are frequently using rough / bush strips with taller grass tufts which can snag it.
I ordered my fin antenna from https://www.deltapopaviation.com/Transponder_Antenna.html and it works perfectly with my Trig TT21 Mode S transponder. (I frequently fly in military / controlled airspace).
When installing the antenna make sure that you leave enough space for a square metal ground plane (120mm x 120mm) or a ground plane of 4 wires or rods radiating from the antenna base to a length of 1/4 the wavelength (68.8mm length). (refer to your specific Transponder manual for exact ground plane requirements).
Regards, Dave

Mine is also installed between the landing light and pitot tube.

Learjet what VHF antenna did you use to compliment the transponder antenna and where is it mounted? I'm concerned my radio antenna, which is mounted on the nose, is a bit close to the transponder antenna.

 

[Mayfield]

Since the comm frequencies are in the 130 MHz range and the transponder frequency is over 1000 MHz, I suspect there would be minimal frequency bleed. I have observed far less than the recommended 36-inch separation between these antennas. On many smaller aircraft I see 20-25 inches without negative consequence.

I think we have a few radio gurus on this forum that might give a better answer.

Jim

 

[Tyger]

Mine is also installed between the landing light and pitot tube.

Interesting... would you have a photo of that? There's not much room between those two.

 

[Learjet]

Mine is also installed between the landing light and pitot tube.

Learjet what VHF antenna did you use to compliment the transponder antenna and where is it mounted? I'm concerned my radio antenna, which is mounted on the nose, is a bit close to the transponder antenna.

Nomie, my vhf antenna is mounted on a bracket on the mast. No interference issues at all. My previous M16 had the vhf antenna mounted on the nose in front of the windshield and the transponder antenna just beneath the passenger seat. No issues there either so I'd agree with Mayfield about the adequate frequency gap.
Regards,
Dave

 

[nomie]

Interesting... would you have a photo of that? There's not much room between those two.

Sure. I unfortunately don't have a photo of the inside and the gyro is currently in maintenance, but the transponder antenna is mounted to a ground metal plate on the inside, around the size that Learjet described. As you can see my two antennas are mounted very close together



Thanks Learjet.

 

[Tyger]

I am impressed that you squeezed it into such a tight spot! I have had to change the bulb on my landing light, and getting at that mount when all the other behind-the-panel stuff is in place is its own special nightmare.
My transponder antenna is between the light and the front wheel. My radio antenna is mounted to the keel just in front of the empennage.

 

[schmoe90]

I have had to change the bulb on my landing light, and getting at that mount when all the other behind-the-panel stuff is in place is its own special nightmare.

I discovered it really, really helps to take the windscreen off

 

[Tyger]

Hahaha, oh DEFINITELY. I think I've taken mine off about a hundred times by now...