Splicing 496 antenna cable

[Bubblehead]

The GPS antenna for the Garmin X96 series is huge! Here's a picture of it next to a 1/4" drive ratchet.



I want to route it in better paths but don't want swiss cheese for panels. Is it possible to splice a smaller connector into the line to facilitate routing the antenna cable a better way or locating the antenna in a better place? Or is it better to mount a BNC bulkhead connector close to the antenna and run new cable from the bulkhead to the 496?

Perhaps a BNC to SMA adapter at the 496 and at the antenna location?

I'm sure someone out there has an elegant solution to this common problem.

[aerhed]

I've spliced them with success, but how bout an SMA union somewhere? Then you'd just have an SMA for max dia.

[Mel]

Unless you need to remove the cable routinely, just cut off the connector, run the cable and install a new BNC connector. That's all the original is.

[Ironflight]

In building our -3, I had three of those little tiny antennas with the huge BNC connectors on the end to run through our glareshield deck, and I didn't want giant holes. I also wanted reliable connections. So I did a little searching on that small-diameter Coax (from memory, I think it is "RG-174"), and ordered appropriate BNC's from Mouser. The challenge was finding a crimper with the right die for them - after a couple of weeks of finding $80 die sets, I ran across a dusty crimper on a dusty shelf at our Fry's that had the right sized die for something like $25. I have quite an assortment of crimping tools!

Morale - it is easy to cut the end off, and conceptually easy to put on a new end - but you're gonna need new tools to do it right!

Paul

[flyeyes]

Originally Posted by Bubblehead

T
I'm sure someone out there has an elegant solution to this common problem.

I don't know if it's elegant, but I had exactly the same issue, and didn't have any spare connectors on hand.

I just cut the cable in the middle, and spliced it with solder and heat shrink. 5 minutes, it looks a little kludgy but works fine.

[rocketbob]

RG-174 is horribly lossy coax. Your best bet is to run RG-400 to a bulkhead connector near the GPS antenna and then put a new RG-174 BNC close to the antenna. And you would get stronger GPS signals. Also you can get screw-on BNC connectors for one-off's like RG-174 so you don't need a crimper. I don't think velocity factor would be a problem when shortening the antenna but I could be wrong.

http://search.digikey.com/ca/en/prod...1157-ND/160092

[Loboflyer]

Unless there's other constraints involved, I agree with Bob. RG174 is nice for exposed flexible runs but pretty crummy for anything else. I use it at low frequencies (< 100 MHz) as bench interconnects to test equipment. It is lossy and not well shielded at high frequencies.

I don't recommend solder and heatshrink splices, as flyeyes suggests, at GPS frequencies when real coax connectors aren't that hard to come by.

I can't see any reason why shortening the antenna would cause issues (that show up as something we care about) due to velocity factor -- once the separate satellite signals enter the antenna, they all travel together with the same relationship to the receiver. The only reason I can think of to not shorten the antenna or use better coax is if there's a minimum loss specification that must be met to avoid overloading the receiver, which IMHO is a bad design in the first place, especially on the near myriabuck GPS units that ask for it (e.g. GNS-430).

[Bubblehead]

I had to make an Allied Electronics run today to pick up a few more pins and sockets to finish some connectors tonight so added one Amphenol BNC connector.

As always, the people on (in?) VAF have come through with some good info on how to overcome an old problem.

Thank you!