Welcome to the APRS Page of AA9NV

A page exhibiting some of our work and passion for APRS

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Location Data    Digipeaters and Igates    Radios    Installations    GPS   

If you have any comments or corrections, please email - aa9nv at arrl dot net

The amazing world of APRS, use one of the locators to see where someone is beaconing from today!

Location Data:

Click on the thumbnails for high resolution pictures showing tracking data

Screen Shot of UIView for North Carolina and part of VirginiaJFindu track of AA9NV-5 Richmond to DC on 02/09/07JFindu track of AA9NV-5 Richmond to Chapel Hill on 02/12/07JFindu track of AA9NV-5 Round trip Chapel Hill Durham on 02/19/07 after the NC4SU-10 installation

Click on the call sign links to view positions

Call sign

Tracker type


APRS Symbol



UIView PK88







TT3 Plus


Red truck



Future use


Future use




Circle 5



Future use


TT3 Plus


Circle 7



Future use


Circle 8



TT3 Plus


Circle 9

Placer 450/Car


TT3 Plus





UIView PK88






GE Delta

Green Star



APRS find


APRS jFind

Digipeaters and Igates:

Digipeaters and IGates

They are incredible and their useful range surpasses regular analog voice by approximately 25 - 30% thereby improving coverage and reliability to stations that would otherwise be marginal contacts. During emergencies this could be the difference between a failure or a successful outcome.

They pass a lot of position, weather and text data that make APRS accurate, reliable and versatile for both everyday and emergency communications.

Can I run an IGate on my Linux machine while IRLP is running? There doesn't seem to be an answer but probably depending on the amount of programming one is willing to invest. :)

IGATE Web Servers

The AA9NV-10 IGate in central Wisconsin

Sites include a near current view of the Web Server console so viewers can see the position of stations and radar in almost real time, about 2-5 minutes delay.


KI4HZP in Eastern Florida

N9QIP in south central Wisconsin

W.I.N. Wisconsin Interstate Network APRS page




TinyTrak SMT installed in a Maxtrac D33. Also wired to interface with an MFJ 1274 TNC and the laptop.

Click for a bigger pictureClick for a bigger picture

TinyTrak 3+ and a Garmin II+ installed on a Maxtrac D33


General Electric MVS mobile radio (NPH20) with a Globalsat ET-102 installed. A 7805 supplies the 5 VDC, capacitors are normally 100f on the 12V side and 10f on the 5V out (see circuit in GPS section). Important note here, if you don't mind the heat you can leave the 7805 hanging loose but the heat will be significant. Being a firm believer in heat kills for electronics, this 7805 was mounted/slid under the circuit board and sits directly on the frame of the radio. The 7805 stays very cool during normal operations but even with extra loading on the 7805 for testing, the warmth was negligible when frame mounted. SirfDemo running data from the the MVS's onboard ET-102.The right picture shows a level converter connected to the GPS end of the Tiny Tracker. The level converter is powered by the tracker, which doesn't even get warm because there is so little power draw. The advantage here is a computer using standard GPS data can be connected to the TT for whatever purpose, like running Streets and Trips, Precision Mapping, UI-View, etc, that have been tried and tested.

 Pin 9 of the Tiny Tracker radio connector isn't utilized so the GPS TTL data was fed from inside the GE MVS radio through the serial cable to pin 9 with a 10K resistor jumper to the lead side of resistor 14 which has a direct trace to pin 2 of the GPS connector, shorter route than going directly to pin 2. A 10K resistor should allow for programming the tracker as well as normal tracker operation, haven't found that to be so with this GPS/TT so a higher value was used. Tried a 220K, still worked great.

Tiny Tracker programming can be accomplished by two methods for this setup. One is by unsoldering and  lifting one end of the 10K(resistor) or Two, by following these steps:

1 - connect the null modem to the TT and the computer, 2 - unplug the TT from the radio/power source, 3 - plug the TT back into the radio/power source, 4 - click on the read version and see if the TT and computer are communicating, if it is, write configuration and it is done. 5 - disconnect the TT from the null modem/computer, unplug the TT/power and then re-connect. At this point the TT should return to a normal status, three of the TT units tested all worked well using these steps. The programming usually isn't a big deal unless one is constantly changing the parameters. The TT's are usually programmed initially and maybe once later on for a fine tuning session for a particular use and then left alone so it isn't an issue. The big plus is being able to use the same GPS data to feed both the tracker and a laptop.

TT showing a good GPS lock on the TTL data stream, the Trimble antenna is using the same grommet (with a notch cut in it) as the stock power cable. The red led is the 1 Pulse Per Minute (PPM) of the GPS and blinks in time with the received satellite data, a heartbeat of the system indicating life. :)

MVS radios are very easy to program with the programming cable and software, both readily available on the web.  The APRS frequency is out of the normal band for the 150+ split radios so use CTRL E to enter the number. Weather frequencies were entered for the last six of sixteen channels but the transmit couldn't be left un-programmed so instead of running the risk of transmitting on a weather frequency, 144.39 was entered on each one. Now, if the tracker isn't unplugged when listening to the weather, the unit merely transmits on the APRS frequency for a flash and continues to monitor the weather. If you are thinking about trying this, please be considerate of the amount of traffic in your area, this unit is generally in a very quiet area and beaconing in to our IGATE direct so the chance it might transmit on another beacon is very minimal. Unless the carrier drops long enough for the TT to have a clear frequency, the unit won't transmit anyway.

The audio from the MVS is very sufficient for the TT and the volume may be left turned all the way down, or one bar up, and still maintain reliable signal detection. The pictured units have a switch for the audio installed, one way is quiet and feeds just the TT and the other way feeds the TT and the front speaker in the OEM configuration. TT audio is always on.

NOTE: If a load resistor is used when just feeding the TT, the volume may need to be turned up about half way before the TT will receive a reliable signal for detection. The audio is 4 ohm. The standard configuration for these is to not use a resistor to avoid turning the audio up so far. Side note: Motorola units do use a floating ground and some choose to use a resistor inline to avoid letting the smoke out of those systems.

While not absolutely necessary, these radios were fully aligned to center on 150 MHz using the manual for all tuning sequences, an HP8924C calibrated service monitor, a Simpson 260 and a BK tools digital volt meter.

GE MVS APRS wiring, the resistor to ground for the audio has been lifted and heat shrunk. The center picture shows the factory foam in place, it molds around and holds the added components in place beautifully. The right picture shows the coin battery holder with a CR2032 installed and connected to the VBAT, pin 3, for additional long-term memory back up. There isn't a good picture of the bottom of the GPS units, rubber feet are installed to keep the GPS off the metal shields and from moving around, movement is nearly impossible with the stock foam molded to the components and holding everything in place. The Tiny Tracker with a level converter installed. The level converter fits completely inside the housing and performs very well.

GE MVS with an SMT Tiny Tracker and GlobalSat GPS installed in the bottom of the radio. The serial cable has been rewired to allow the level converter, shown below the radio, to be used for computer navigation at the same time the Tiny Tracker SMT is operational. The rewire also allows the TT to be programmed via the serial cable. LED's are the SMT indicators connected with 1K resistors and mounted in the control head of the radio. Front panel LED's are not in the same sequence as the TT units: power, GPS valid, carrier detect and transmit. Nice package, power cable, GPS antenna and cable, and RF antenna cable - no other boxes, harnesses, mounting hassles or configuration issues.

All Tiny Tracker kit assemblies, serial cable connections and GPS installations were accomplished using a Weller WESD51 soldering station. This is one of the best purchases made for working on electronics. The WESD51 heats up very quickly, maintains temperature and is very comfortable to use for extended periods. A fantastic unit through and through.

The part numbers used on these set ups:

Mouser part for power connector - vehicle side (Mouser # 571-7700701)

Mouser part for pin for power connector (Mouser # 571-7701441 Socket 20-14)

This data is posted on the web but it's accuracy has not been verified:

Microphone housing 22-55-2102 Mouser p/n 538-22-55-2102
Pins 16-02-1112

Power connector (vehicle end)
Housing 03-09-1032
Pins 02-09-1104

Accessory Connector (mates with external stock pigtail to system board.)
Housing 39-01-2140
Pins 39-00-0059
Extractor tool 011030044

Mouser part for mic plug (Mouser # 538-22-55-2102)

Mouse part for pin for mic plug (Mouser # 538-16-02-1116)

There are a number of web sites posting information about the MVS.

N0RQ - How to set the MVS up for Amateur Packet and APRS use, programming information

VE3FYN - easy to follow instructions for IRLP wiring, fuse replacement, nice graphics for options and pinouts for the mic and option connectors

W4XE - nice write up and graphics for interior components and layout information, connector data

ARCsquared - great collection of manuals

KD4BBM - cool pieces of MVS data, KPC3 connection information, excellent graphic of the power and option connectors from the manual showing the pins and their usage

Hall Electronics - Model number break out

GE MVS add on ANI encoder decoder board

Probably should have just an MVS page but for now, the data will be posted here.

Some of the units came in with what are believed to be Automatic Numerical Identification (ANI) decoder encoders from Cimarron Technologies. The basic function is to send a short unique data burst every time the user pushes the Push To Talk (PTT) on their radio. The data burst tells the receiving end who keyed the radio. Expanded ANI functions allow for additionally enhanced radio operations. The connections are shown in the pictures in case someone needs to perform the same or similar work.


PK-88 and a D33 low split Maxtrac

The UIView IGate uses this PK88 and Maxtrac VHF low split 16 pin

One nice unit consists of a Delta radio, MFJ-1274 TNC running UI-DIGI, and a Motorola power supply. Power is about 30 watts with the deviation at 3.8 kHz.



Impala APRS installation

Diamond 7900, Trimble GPS antenna, Larsen NMOQB

GE MVS, Trimble Placer 450, Tiny Tracker 3+

 The MVS units are 150 high split but they tune to 144.390 at or better than factory specifications easily. These units have very hot receivers and do an excellent job. They are efficient and produce very little heat even when keyed down for longer transmission times. The Maxtracs draw more amperage, put out the same or less power, and heat up like crazy when used for extended transmit times.

The Trimble Placer 450 is a neat GPS unit. The GPS is easy to set up using GPSSK. Three of the last five units all came in with dead memory batteries and they cost about $8 dollars each. The interface between the Placer and the Tiny Tracker is a shielded two conductor cable using number 2 and 5 from the MDT DB9 port. Supposedly one can use the Radio DB9 port with a null modem but I haven't tried it. The antenna connector is an SMB.

The main reason for changing the tracker set up from the original Maxtrac/TT was to automate the operation, change equipment locations, use a higher quality GPS unit, and put out a few more watts of power. Normally power isn't too much of a concern but this vehicle travels through a lot of open country side and a few watts extra may help, especially in light of changing from the 7 db gain antenna to a unity gain, ouch. The GE MVS and the Trimble both have and are wired for ignition sense. This means that both units are off until the car is started, very handy. Nothing to turn on or off and no worrying about batteries being dead the next time the vehicle is used. The equipment is mounted in the trunk, under the rear deck, so it is mostly out of the way. The Trimble has satellite settings in it that insure more accurate location transmissions. The MVS puts out about 10 more watts than the previous Maxtrac D33. Goals were all accomplished and the results are a very nice installation that performs very well.

Pictures courtesy of KI4HZP, nothing like a little Florida sunlight to make the day better.

Ford Van Installation

Pictures and more data to follow.

KC9KUJ-2 tracking through Minnesota, Northern Iowa, and Missouri

The installation is a GE MVS with the GlobalSat GPS installed in the bottom of the radio as explained under the Radios GE MVS section above. The NMO mount is a Maxrad BMF-NC terminated with a male Amphenol TNC connector from Mouser. The crimp tool from Mouser is really a nice tool and does a beautiful job. The antenna is an Antenex Chrome QW 1/4 wave factory cut for 144 MHz.

The Tiny Tracker 3 plus is on the end of an installed serial cable, also explained above.




The Globalsat ET-102 is looking like a great little GPS unit for APRS. Still testing the little unit but so far it has been an exceptional performer on the bench and in the field. The first article I found was was by N5NA and gave me a good start on what to expect. I used SirfDemo to set the GPS for 4800 NMEA out and all of the sentences listed. After operating a few different configurations, the GPS was programmed to send only the G sentences and only every two seconds. As noted in Byonics literature, it appears as though the Tiny Tracker didn't like that constant stream of data going into it. :) The GPS receiver is pretty hot (sensitive), -170 db.

Globalsat ET-102 GPS engine board and dimension and a level converter

The level converter is not needed for using the GPS unit with the Byonic's Tiny Tracker, check the TTL box, but is needed when connecting to a laptop. The level converter pictured is inexpensive,  functions well, and is from an online auction. There are some simple TTL converters that don't use the MAX232 chip, haven't tried one yet.

For computer connection and testing: connect the GPS pin 11 (RX) to the level converter TX, connect GPS pin 12 (TX) to the level converter RX, and one of the GPS ground pins which are all tied together 10, 13, 16 or 18 (GRD) to a level converter ground.

The level converter will use 4 connections TX, RX, GRD and VDC (5). An inexpensive level converter in kit form was purchased online and came with a db9 connector for connection to a standard serial cable.

On the GPS, connect 5 VDC+ (60ma) to pin 1 (powers the unit) and pin 2 (powers the active antenna), and ground to pin 10, 13, 16 or 18.

If a 5 volt supply is needed, look at the 7805 voltage regulator articles (1 amp capacity) or do a search online for a simple circuit. Some don't use the 100nf capacitor on the 5V side.

circuit diagram  picture of 7085 regulator Graphics by Tomi Engdahl

This unit uses an external antenna with an SMB connector. The model numbers used for testing are Trimble antennas part # 34048-00 and  40767-00. Not really sure but it seems as though the 34048-00 unit works a bit better, it is slightly thicker than the 40767-00. Trimble shows a cross reference including 56237-00 for using any of these three units. A generic antenna was tried, not quite the same performance but close.

The GPS and converter were tested and work great with VisualGPS, Microsoft Streets and Trips, and Precision Mapping Streets and Traveler (use F11 to connect the GPS and show the dashboard feature, really sweet).

The ET-102 generally acquires a location lock in under two minutes from a cold start and includes Differential GPS with Wide Area Augmentation System (WAAS), Sirf calls this Satellite Based Augmentation System (SBAS), within a minute or so after the initial lock. Specification calls for 48 seconds average. Generally seeing a location pattern of about 10 meters or less in the shack. The three circles in the map view of the screen shot are 5, 10 and 15 meters. The last screen shot is showing the unit with Static Navigation turned on. In this mode, if the unit isn't changing location it maintains a static output. This is a really nice feature that prevents false beaconing due to signal changes from back scatter, buildings, satellite movement, etc.

SirfDemo screen shots

Another tidbit of information, Globalsat receiver does a nice job with an external antenna stuck on a kettle lid in the shack on a shelf. Why is that important? Many GPS units do not receive indoors but the ET-102 does so with a 3d + DGPS lock. In comparison, the Placer 450 will not receive any satellites indoors with the same antenna and set up. The Placer receiver must be worse than the Globalsat but there aren't any available specifications posted for the Placer unit. The Placer performance would be on par with the Garmin II and maybe the II plus units. The Garmin III and V units receive about equally as well as the ET-102 when set up with an external antenna.

The external active antennas enhance the satellite signals and thereby the satellite acquisition capability of the GPS units tremendously. A Garmin V will barely obtain a location lock indoors using the stock antenna, but with an external active (powered) antenna, location lock is within a very short amount of time and maintained.

The units can lose their programming after some months of sitting in storage. There is a place for VBAT to connect a back up battery supplying 2.5 - 3.6 VDC. Tried this but further testing is necessary. The units do not lose their programming for a month or so sitting completely un-powered and without a battery back up. Received an email from GlobalSat with their recommended VBAT connection, the backup battery is connected straight to pin 3 and no other changes were noted for powering the unit. Installed a coin cell holder and CR2032 battery for memory back up (battery has a shelf life of 10 years). The GPS uses 10 A for memory back up and the coin batteries have 230 mA so they should maintain for years. 1000 A = 1 mA


We have been running digital modes for a few years and would like to hear about your experiences while operating any digital compared to voice modes over the same or similar communication frequencies and paths.

One example could be working an FM VHF or UHF repeater that is co-located or in close proximity with or to a 2 meter APRS digipeater from your mobile. Another example could include SSB voice compared to PSK31 on the same HF band communicating with both modes to approximately the same location.

Did you hear and work them both equally or very differently? What impacted or influenced the particular communication the most, frequency, mode, propagation, etc?

Feedback and articles read so far all indicate that digital modes, especially APRS, out perform analog communications. Thanks to all who have sent messages explaining your experiences.

Please drop us a note

Byonics - TinyTrak GPS Position Encoder

Byonics - Micro-Trak could have some great applications.

Wisconsin Valley Radio Association

The use of any materials from the site is done at your own risk.

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