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First Track!

Guy Prevost

Well Known Member
aprs.fi/n678PR

This was a test with the magnetic based antenna, stuck behind the roll bar in the cockpit. Next I'll install the whole thing with a J-pole in the wingtip.

I missed getting quite a few packets out, but considering the sub-par antenna placement and the fact that I was below the surrounding terrain for much of the flight, I'm satisfied.

Guy
 
good job !

I made my initial APRS track(s) with the little magnet mount antenna attached to the forward rollbar of my RV-8. IT worked great ... then again, I was at 11,500' :)

You'll love the setup with the j-pole.
 
IMHO you won't find the J-pole does any better, if not worse Save yourself the hassle of putting it in the wingtip. I and others have regularly observed that the fuselage appears to shadow the transmission to the opposite side of the airplane. In other words, with the J-Pole in the left wing, stations on the right side of the plane won't see your transmissions.

I'm frustrated with the J-pole enough that I'm about ready to install a VHF antenna in a wing inspection cover.
 
IMHO you won't find the J-pole does any better, if not worse Save yourself the hassle of putting it in the wingtip. I and others have regularly observed that the fuselage appears to shadow the transmission to the opposite side of the airplane. In other words, with the J-Pole in the left wing, stations on the right side of the plane won't see your transmissions.

I'm frustrated with the J-pole enough that I'm about ready to install a VHF antenna in a wing inspection cover.

So far, you are proving to be correct. I'm getting almost nothing out of the J-pole antenna. I'm going to shift it in the wingtip to give it a tiny bit of vertical polarization, but I may have to seek other options. I am pretty intent on having the entire installation in the wingtip--installing elsewhere in my -8a is not worth the time investment.

Other options I'm considering--The byonics -1 8.75" whip installed on a bracket near the top of the wingtip and facing down. An inch or two would poke down through the wingtip. The bracket would be attached to the outboard rib so the wing would be a (somewhat one sided) ground plane.

One of the wart type antennas shown in a thread on this side, mounted under the wingtip.

A whip antenna mounted to the outboard wing inspection panel.

Comments or ideas welcome!

Guy
 
I looked around for a couple different installs of the j-pole in the wingtip. Here is what I found ...

tipjpole2.jpg


tip1.jpg


28_wing_tip.jpg
 
My install matched the second photo pretty closely. I just moved it to center it more in the curve of the leading edge and will test later.
 
Watching

Looking forward to a summary of what works best. Wish to install one of these set ups soon. Need some one to dummy it down for me. This is all greek to me.

Rick
 
IMHO you won't find the J-pole does any better, if not worse Save yourself the hassle of putting it in the wingtip. I and others have regularly observed that the fuselage appears to shadow the transmission to the opposite side of the airplane. In other words, with the J-Pole in the left wing, stations on the right side of the plane won't see your transmissions.

I'm frustrated with the J-pole enough that I'm about ready to install a VHF antenna in a wing inspection cover.

Something isn't right. The j-pole in the wing-tip, while breaking a bunch of antenna rules, has been proven to work very well in a lot of RVs. I've seen the tracks, they are solid.

With eight watts of power at altitude we should be able to get a good track with a coat hangar. Be sure you do not have an antenna connector problem. Check the center conductor in the SMA to make sure it isn't damaged or pushed back into the connector. I had a BNC center pin to fall back into the connector but I was still getting a somewhat decent track even though the only antenna was the coax inside the cabin.

The absolute best antenna is a 1/4 whip on the belly of the plane. But the j-pole has proven to work just through brute force.
 
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Mine looks pretty much like the second photo that Glen posted, only much uglier. I've never posted any pictures of that wingtip because it is a complete horror show in there housing all kinds of tinker toys that just work.
 
Something isn't right. The j-pole in the wing-tip, while breaking a bunch of antenna rules, has been proven to work very well in a lot of RVs. I've seen the tracks, they are solid.

With eight watts of power at altitude we should be able to get a good track with a coat hangar. Be sure you do not have an antenna connector problem. Check the center conductor in the SMA to make sure it isn't damaged or pushed back into the connector. I had a BNC center pin to fall back into the connector but I was still getting a somewhat decent track even though the only antenna was the coax inside the cabin.

The absolute best antenna is a 1/4 whip on the belly of the plane. But the j-pole has proven to work just through brute force.

Like Sam says I have had great luck out of mine. Is it 100% optimal? Nope but it does not have to be at the power and altitudes we run.
 
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Hmmm......

Guy - try a new position and check the sma connector as mentioned here. If it is still wonky, we will get a new one for you to try. Just send me a PM or an email.
 
Success! Again, I think....

Pete kindly sent me a new antenna even though I had no idea whether I had a problem with my rig or the antenna. I had previously repositioned my antenna, with no better results. I decided to be more systematic this time around.

This evening I removed the wingtip, clecoed it upside down onto the top of the wing, and pulled the airplane out into clear view of 10600' Sandia Peak and its receiver.

I powered up the transmitter, which yielded no results beyond a green LED on the device showing that is had good gps lock.

I then connected my 1/4 wave whip antenna. Powering up the transmitter netted an immediate good path.

Step 3 was to install Mr. Howell's replacement antenna. It also got immediate good paths.

I cleaned up the install and took a couple of laps around the pattern. Success! My guess is the original J-pole was damaged in shipping. Thanks to Pete Howell and his kids for going above and beyond.

APRS10-21-13-M.jpg
 
Sweet!

We found another bad one in the field - it was the connector. We might have got some bad connectors or we might have dorked up the assembly. Got them both fixed now.

Thanks Guy for working with us to get it fixed. Happy Trackkin'!!!
 
For wingtip installs, the "Howell-er" j-pole antennas a great performers.

And "yes" - great service and support ! Hopefully his kids will always need beer or pizza money :D
 
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