Comparing sensors in a Garmin Oregon 400i, a Garmin 60CSx and the Yaesu VX-8

My house temperature was 65-66 degrees when I turned on my VX-8 and the sensor registered 77 degrees. Later on it got to 82 degrees. Well, that's the temperature inside the VX-8 so I guess some energy is converted to heat, and I was not transmitting. So all I can say, the VX-8 would make a dismal rectal thermometer... But if you want to know how hot it is in the unit, well I guess the number is in the ballpark.

Altitude:
I compared three instruments, a Garmin 60CSx GPS, a Garmin Oregon 400i and the VX-8. I looked at both GPS and barometric altitudes.

	Barometric altitude	GPS altitude
Garmin 60CSx	1072	1069
Oregon 400i	1081	1079
Yeasu VX-8	1092	1030

Measurements were taken in a single location (my living room) at about the same time, meaning very little change in the GPS constellation. The Garmin units show consistency and a difference of 9-10 feet. The VX-8 is in the ballpark but the GPS altitude is not as good. According the the topo map the altitude is 1055. Since I was not in the basement, maybe I need to add 8-10 feet or so and the map contour lines definitely predate the house...

My conclusion is not to try to land a plane using any of these three instruments only... Otherwise, gosh, it is good enough for me.

I also checked the GPS' precision in location and here the news are excellent! The table below shows the decimal part of the minutes in both longitude and latitude numbers, all in WGS 84 datum.

Garmin Oregon 400i and 60CSx	Yaesu VX-8
,758	.765
.878	.874

Now, this is only anecdotal data, a single measurement in the comfort of my living room, not taken in any extreme type of weather and conditions. But for me it is good enough.

My new Yaesu VX-8R radio/APRS

This is my new Yaesu VX-8R radio, A small but rugged and waterproof handheld which has a built-in GPS chip in its speaker mike and not only displays my location (in lat/long, WGS 84) on its screen, but can also send it via APRS, to the entire world, given it can reach an internet gate (i-gate).

If its transmissions make it to an i-gate, my position can be checked on several websites including my own K9CHP. Just scroll down to the Where am I page.

But even if I am truly hiking in the boonies, my VX-8R can transmit my position to my truck where it will be kept both on the Kenwood TM-700a mobile radio and the Garmin 60CS GPS. The TM-700a is now out of production and has been replaced by the RC-D710

Another possibility is to use my Kenwood TH-D7AG handheld radio that can be connected to my Garmin 60CSx GPS. This is the seup shown below. I trd using it in the field but the radio is fragile and not waterproof, so you have to protect it a lot and the connecting cable not only tends to get snagged but disconnects quite often, so the entire setup is of questionable field value. But it can be left at base and now they can have a precise idea of my whereabouts and anybody elxe using APRS in that area.

I can also connect the TH-D7AG/60CSx to a laptop and have the locations appear on screen. But the software I use needs internet connection to work at its best, so it won't be functional everywhere. The TH-D7AG is now out of production.





And here you can see how my location looks like on the GPS screen. The blue flag is the last waypoint received. I did change the scale to a large display so the new waypoint will be distinct from the existing ones. But even if it is not clear enough on screen, find waypoints near current location will give the desired results.

I hope to put the system into use in SAR training with Eagle Valley Search Dogs. The nice thing is that the VX-8R can be used by a person without an Amateur Radio licence as it is a simple remote APRS beacon and I will be its control operator. The person carrying it will not have access to any function other than turning the unit off, if so requested on our SAR network.