Are GPS antennas backward compatible?

Chip Sylverne

Chip Sylverne

Final Approach
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Quit with the negative waves, man.
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I know a waas upgrade requires an upgraded antenna. But let's say you have a non-waas GPS and need to replace a tso C-144 antenna that is suspect, or need to temporarily replace it with a known good TSO C-190 antenna to troubleshoot. Would the waas antenna work with a non-waas receiver?
 
My plane came with a WAAS antenna hooked up to a non-WAAS 430.
 
OK, lets get real. There is no such thing as a WAAS antenna. There may be some antennas approved under a couple of TSOs, but that does not give them the title of "WAAS antenna." A piece of limp spaghetti in a copper septic tank may be erroneously called a wass antenna, albeit a rather poor one.

I particularly have a gps antenna that I universally recommend that is small, lightweight, and of Taiwanese origin with no tso in its pedigree but measurably outperforms most tso antennas at one-quarter of the price. It it a wass antenna? Yes, i claim that it is under the "or equivalent' in the gps manufacturer's installation directions under "antenna installation".

Jim
 
weirdjim said:
OK, lets get real. There is no such thing as a WAAS antenna. There may be some antennas approved under a couple of TSOs, but that does not give them the title of "WAAS antenna." A piece of limp spaghetti in a copper septic tank may be erroneously called a wass antenna, albeit a rather poor one.

I particularly have a gps antenna that I universally recommend that is small, lightweight, and of Taiwanese origin with no tso in its pedigree but measurably outperforms most tso antennas at one-quarter of the price. It it a wass antenna? Yes, i claim that it is under the "or equivalent' in the gps manufacturer's installation directions under "antenna installation".

Jim
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At the risk of offending one of the few posters on this board that I truly respect, let's get even more real.

You know what he meant.
 
JOhnH said:
At the risk of offending one of the few posters on this board that I truly respect, let's get even more real.

You know what he meant.
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Chip PM'd me and i was privately able to help him in ten words. I promised him i'd give the full public answer in this ng. sorry I took so many words in the full answer.

Jim
 
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The install manual for your GPS will almost certainly contain the minimum specs for the GPS antenna, along with a list of "suggested" antennas that meet those specs.
 
I figured that you might need better antenna/cabling/etc for WAAS due to greater free space losses from GEO than LEO. Is that not the case?
 
GeorgeC said:
I figured that you might need better antenna/cabling/etc for WAAS due to greater free space losses from GEO than LEO. Is that not the case?
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I haven't looked closely at the antenna specs, but the install manual will typically require better cable for a WAAS install (RG400).
 
bradg33 said:
I haven't looked closely at the antenna specs, but the install manual will typically require better cable for a WAAS install (RG400).
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I respectfully disagree. The stupid-@$$ manual SUGGESTS (expensive, heavy) RG-400 and then goes on to say that there has to be 7 (or so) dB of loss, which translates to 15' or so of coax, which means you coil up 4# (and $8) of excess coax. That's stupid when you could use (cheap, light) RG-174 with no excess to carry around as ballast.

Why does the engineer specify RG-400? For the same reason a dog licks his b@!!$. Because he can.

Jim
 
weirdjim said:
I respectfully disagree. The stupid-@$$ manual SUGGESTS (expensive, heavy) RG-400 and then goes on to say that there has to be 7 (or so) dB of loss, which translates to 15' or so of coax, which means you coil up 4# (and $8) of excess coax. That's stupid when you could use (cheap, light) RG-174 with no excess to carry around as ballast.

Why does the engineer specify RG-400? For the same reason a dog licks his b@!!$. Because he can.

Jim
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Sounds like the aviation industry...:frown2:
 
Chip Sylverne said:
I know a waas upgrade requires an upgraded antenna. But let's say you have a non-waas GPS and need to replace a tso C-144 antenna that is suspect, or need to temporarily replace it with a known good TSO C-190 antenna to troubleshoot. Would the waas antenna work with a non-waas receiver?
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This actually a great question for Garmin tech support. I'm pretty sure the answer is yes.
 
I don't know the answer....but, I do know that a WAAS GPS antenna is an "active" 9V antenna....where as a "non-WAAS" is not active and not powered.

I'm gonna guess.....and say they are not backward compatible. But, you could always give it the smoke test and let us know how it works out. :D
 
Checkout_my_Six said:
I don't know the answer....but, I do know that a WAAS GPS antenna is an "active" 9V antenna....where as a "non-WAAS" is not active and not powered.

I'm gonna guess.....and say they are not backward compatible. But, you could always give it the smoke test and let us know how it works out. :D
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Nope. Both are active, 4.5V-14v, same impedance, same freq.range, same Db signal amplification. Spec sheets are wonderful thing.
It really makes me question why a new antenna is really needed for an upgrade, other than incremental $. I guess there must be something in the TSO's.
 
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when I upgraded the 430 to WAAS in the Six it required a coax change to the RG-400 and new antenna. Without comparing the specs...who knows?
 
Checkout_my_Six said:
when I upgraded the 430 to WAAS in the Six it required a coax change to the RG-400 and new antenna. Without comparing the specs...who knows?
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I respectfully refer you to post #9.
 
Well, the smoke stayed in and got satellite position lock in about 20 seconds. Couldn't flight test because of nasty wx, but don't anticipate any problems.

Thanks everyone, especially Jim
 
Checkout_my_Six said:
I don't know the answer....but, I do know that a WAAS GPS antenna is an "active" 9V antenna....where as a "non-WAAS" is not active and not powered.

I'm gonna guess.....and say they are not backward compatible. But, you could always give it the smoke test and let us know how it works out. :D
Click to expand...

This answer sort of reminds me of the folks that wrote a dictionary that defined a crab as "a small red fish that walks backwards". Perfect, except that they are not small, nor red, nor a fish, and do not walk backwards.
You could have stopped at "I don't know" and been batting a thousand. After that, 0 for 3.

Jim
 
weirdjim said:
This answer sort of reminds me of the folks that wrote a dictionary that defined a crab as "a small red fish that walks backwards". Perfect, except that they are not small, nor red, nor a fish, and do not walk backwards.
You could have stopped at "I don't know" and been batting a thousand. After that, 0 for 3.

Jim
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Hey....I just do what I'm told. :D
 
Next question....I have an old GPS and want to install an ADS-B transponder. Can I replace my current GPS antenna with one for the ADS-B and split the signal to my old GPS?
 
cgrab said:
Next question....I have an old GPS and want to install an ADS-B transponder. Can I replace my current GPS antenna with one for the ADS-B and split the signal to my old GPS?
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Yess, just as soon as I'm done with my ~$25 GPS splitter instead of the $100+ ones on the market today :cheerswine:

Jim
 
weirdjim said:
I do not call a spade a spade. I call it a f&c$ing SHOVEL!!!
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And that’s why I enjoyed Jim’s forum at Oshkosh so much. By the way, that free 182 window shade I acquired in the forum is amazingly effective. My wife even noticed and asked whether we really had to take it down to start the engine. Thanks again Jim!
 
aggie06 said:
And that’s why I enjoyed Jim’s forum at Oshkosh so much. By the way, that free 182 window shade I acquired in the forum is amazingly effective. My wife even noticed and asked whether we really had to take it down to start the engine. Thanks again Jim!
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You are too kind, sir. It is worth seven days of driving 4800 miles to give a one hour forum, but well worth it in my life.

It is kind of neat to be able to SEE THROUGH a window shade, isn't it? You get 5% vision and 95% reflection from that sucker.

Jim
 
weirdjim said:
OK, lets get real. There is no such thing as a WAAS antenna. There may be some antennas approved under a couple of TSOs, but that does not give them the title of "WAAS antenna." A piece of limp spaghetti in a copper septic tank may be erroneously called a wass antenna, albeit a rather poor one.

I particularly have a gps antenna that I universally recommend that is small, lightweight, and of Taiwanese origin with no tso in its pedigree but measurably outperforms most tso antennas at one-quarter of the price. It it a wass antenna? Yes, i claim that it is under the "or equivalent' in the gps manufacturer's installation directions under "antenna installation".

Jim
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Hey Jim, I know this is an old thread, but may I know the Taiwanese GPS antenna that you mentioned? Thank You.
 
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