Trig TN72 Antenna

On Wednesday, April 5, 2017 at 8:24:12 AM UTC-4, Andrew Ainslie wrote:
Your Clearnav, LXNAV, FLARM antennae are all exactly the same as that 300 buck antenna in terms of spec and performance.

And maybe the actual performance of a bargain antenna matches the advertised performance.

If the antenna doesn't perform adequately one would know pretty quickly. It simply wouldn't be able to pinpoint location accurately.

Plus, that antenna was just an example. Clearnav sells a similar one for about $40. I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare. And I've never heard of anyone finding those unsatisfactory, other than occasional location related problems.

Ignoring quality differences, are there technical or FAR related reasons not to do this?

Thanks for pointing out these lower-cost antennas. I see the Amazon antenna has a magnet in the base: that would make it unacceptable to me, since it will be near my compass, unless the magnet can be removed.

I've never been able to understand the FAA regulations about TSO components.. But have been told by several mechanics that its legal to use non-TSO components in an experimental glider. An adsb installation will need to be certified before use, and every two years, and you can also request an inflight test from ATC.

I just opened a GPS antenna to shorten the cable. Why they're sold with
a 10 meter (!) cable is beyond me, however, after peeling off the
sticker on the bottom, you'll see two magnets held in place with
screws. Simply remove the screws and remove the magnets.

BTW, my GPS antenna cable is now less than 12 inches long, has no
magnets, and works just fine.

On 4/5/2017 12:35 PM, wrote:
Thanks for pointing out these lower-cost antennas. I see the Amazon antenna has a magnet in the base: that would make it unacceptable to me, since it will be near my compass, unless the magnet can be removed.

I've never been able to understand the FAA regulations about TSO components. But have been told by several mechanics that its legal to use non-TSO components in an experimental glider. An adsb installation will need to be certified before use, and every two years, and you can also request an inflight test from ATC.

--
Dan, 5J

On Wednesday, April 5, 2017 at 11:45:07 AM UTC-4, Andrew Ainslie wrote:

I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare.

Can you hook up two of the cheaper antennas to your antenna sharing box and gain reliability via redundancy?

Sharing one antenna between multiple GPS reliant devices creates a single point of failure.

On Wednesday, April 5, 2017 at 4:55:52 PM UTC-7, son_of_flubber wrote:
On Wednesday, April 5, 2017 at 11:45:07 AM UTC-4, Andrew Ainslie wrote:

I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare.

Can you hook up two of the cheaper antennas to your antenna sharing box and gain reliability via redundancy?

Sharing one antenna between multiple GPS reliant devices creates a single point of failure.

It also presents a voltage problem unless you use a dc blocker on one of the antennas.

Richard
www.craggyaero.com

There's another thread on this:

https://groups.google.com/forum/m/#!searchin/rec.aviation.soaring/Multiple$20GPS$20antennas/rec.aviation.soaring/ovwxmlKN3Iw

This can help with the quality of reception, admittedly at a mild chance of loss of redundancy should the antenna self destruct mid flight. I can't recall ever hearing of such a case.

My intent is to share an antenna amongst FLARM and 2 Clearnav boxes using the divider described in that post and run the TN72 off a separate antenna located further back in the glider, away from the shared one to minimize RF interference.

On Wednesday, April 5, 2017 at 4:55:52 PM UTC-7, son_of_flubber wrote:
On Wednesday, April 5, 2017 at 11:45:07 AM UTC-4, Andrew Ainslie wrote:

I'm busy fitting an antenna sharing box for my clearnavs and Flarm so I'll have a couple spare.

Can you hook up two of the cheaper antennas to your antenna sharing box and gain reliability via redundancy?

Sharing one antenna between multiple GPS reliant devices creates a single point of failure.

Flub:
For the first situation you would need to have a GPS receiver capable of diversity reception. It would have an A and B antenna connection on the receiver. Doubt one exists.
I've only been using a divider for a couple of years, but yet to have the failure you mention.
Using a 12 volt GPS antenna eliminates the need for DC blockers.
Jim