APRS Near Portland OR?

I'm curious to know what kind of coverage other APRS users get around the Portland area. I just got a Byonics MT-RTG and tried it out tonight. During a 45 minute flight it only got 4 hits. I just had a mag mount antenna stuck to the windscreen bow for the test but it had a clear view out the window. The few hits it did get were probably from 60 miles away. On the map it looks like there should be more repeaters in the area. I was between 1500 & 2500 feet north of Portland. Would that just be an area of poor coverage or would there be something set-up wrong. Other than N-number the settings were pre-set by Byonics. You can see my track at aprs.fi/n962mc .

Also on the way home from the airport I put the mag mount antenna on the roof of the car and didn't get any hits on that 15 minute drive. Yes it was powered. Although I did get a hit last night on the kitchen table. Any ideas?

mcattell said:

I'm curious to know what kind of coverage other APRS users get around the Portland area. I just got a Byonics MT-RTG and tried it out tonight. During a 45 minute flight it only got 4 hits. I just had a mag mount antenna stuck to the windscreen bow for the test but it had a clear view out the window. The few hits it did get were probably from 60 miles away. On the map it looks like there should be more repeaters in the area. I was between 1500 & 2500 feet north of Portland. Would that just be an area of poor coverage or would there be something set-up wrong. Other than N-number the settings were pre-set by Byonics. You can see my track at aprs.fi/n962mc .

Also on the way home from the airport I put the mag mount antenna on the roof of the car and didn't get any hits on that 15 minute drive. Yes it was powered. Although I did get a hit last night on the kitchen table. Any ideas?

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Mark, I suspect your antenna is the culprit. You need either a ground plane type antenna (whip mounted to the metal airframe) or something like a j-pole that is designed to function without a groundplane.

Your ground-based experience is typical for a WIDE2-1 path that doesn't use fill-in repeaters. The little ten-watter is marginal for ground ops if you don't have a really good antenna.

Go ahead and mount a real antenna in your plane and the RTG should be a great tracker.

Mark,

There may be several things that are less than optimal on your antenna setup.

First, the windscreen bow is probably not providing enough of a ground plane for your magmount antenna. You should have roughly 12" x 12" of metal to act as a ground plane.

Second, if you're only gettiing hits 60+ miles away, that means that your fuselage/wings are probably shielding any signal from going down to the ground. You're only being picked up by sites that are horizontal to your location. To fix this, your antenna should be in a location where it "sees" the ground while in flight.

As a reference, I have flown in the Portland area just last week - here's a screen capture of my APRS track.



I use a small antenna that is shaped almost like an egg. It's about 4" long, 2" tall and 2" wide. Here's a picture of it mounted under the passenger seat of my RV-7.



You can take a look at post #5 in this thread for the specs on my antenna.

APRS near Portland

Mark,

I agree with Sam. I fly out of Twin Oaks and get good coverage with an external comm antenna and a Microtrak at 300mw output. Check the links in my signature for some recent flights.