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