“Those who hear not the music, think the dancer mad”

TinyTrak 4 and APRS


Looked like an interesting project..


Two TinyTraks arrive. Simon ordered the ready built version and I ordered the kit - no surprise there. Well, I figured I would have fun building it and save $10 in the process.. Besides if I got stuck I could just refer to Simons ready built one.. But as it turned out the ready built one is surface mount.

I reviewed the extensive documentation, the multiple versions of the documentation and software were a little confusing. Next I made up a power cable to supply 9 volts and a Null modem cable to connect it to the PC. Powered up and used Hyper terminal to run the preloaded diagnostic program. Looked good so far.

Downloaded the recommended Tera Terminal and used it's binary upload feature to load the Tracker program and then reload the diagnostic program. Reloaded the Tracker program and then used the TinyTrak Windows configuration program to read the configuration.


Currently the firmware modules for the TT can only be loaded one at a time. So it can run as either a simple TNC or an APRS Tracker or an APRS Display or a Diagnostic program. There is an alpha module that combines these, but I think we will leave that for the moment.

Tom Tom GPS connection - Very carefully checked the GPS and TT pinouts, connected and powered up the TT. GPS valid LED slowly flashes, then after a while stays on.

Tom Tom GPS lead - DB9 Female 9 pin

TX - Brown -> 2 TinyTrak GPS/Computer PIN
RX - Orange -> 3 TinyTrak GPS/Computer PIN
5V - Red -> 4 TinyTrak GPS/Computer PIN
Ground -> 5 TinyTrak GPS/Computer PIN

TinyTrak GPS/Computer Socket - DB9 Male

1 No Connection
2 Primary Serial data in from a GPS or computer
3 Primary Serial data out to a GPS or computer
4 Power out for GPS (Vin or 5V), or alternate power input
5 Ground
6 No Connection
7 Secondary Serial data out to a computer
8 Secondary Serial data in from a computer
9 No Connection

4800 Baud

TinyTrakRadio Socket - DB9 Female

1 Audio Out
2 Carrier Detect
3 PTT Out
4 J1 Interface
5 Audio In
6 Ground
7 Power In
8 PTT In
9 No Connection

Radio connection - I decided to build the interface for the Kenwood TH-F7E's as both Simon and I have one.

Following a visit to Maplins I replaced the temporary GPS connection with a 9 pin serial connector and started building the Kenwood cables. As with the Kenwood programming interface I had to file down the front face of the plugs in order to get them to properly fit.

Kenwood TH-F7E lead

Mic - Black - Pin 1
Ground - Copper - Pin 6
Audio - White - Pin 5
PTT - Yellow - Pin 3

It took quite a while to get the cables sorted out and to check the TT jumper settings (Remove JP8). Then the moment of truth, would the TT key the Kenwood - Nope. I was tempted to get a beer, but I had a quick think, checked the PTT plug was being grounded on TX and then remembered the Kenwood would doubtless still be in PC programming mode. Corrected this and then used the TT configuration program to successfully key the Kenwood.

My newly acquired FT 817 proved very handy to monitor and adjust the TT TX audio level, hopefully it is correct. Loaded the default TT configuration and prepared to install it in the car.

Of course the power adapter does not fit in the lighter socket properly, so no power and no testing.


Obtained another power adaptor. Powered it all up, but no sign of it on aprs.fi

Ran it on the bench, only to find the Kenwood TX frequency kept changing! Bizarre. Checked the cables, nothing obvious found, just tidied things up.


Reloaded all the firmware again and rechecked the cables. Simon's TT seems to work fine now. Mine still just flashes it's LED's a bit, fails to show GPS valid or to key the rig. More investigation required.

Thoroughly cleaned up the PCB and my TT now works perfectly.


Another try running the TT from the car, but had no luck - this time the Kenwood battery was flat.

Connected the TT 20 character by 4 line display and loaded the RX tracker firmware.

Visited Simon, wired everything up and connected the Kenwood to his colinear. The TRAK4D startup message appeared on the TT display, followed a few moments later by a steady flow of APRS reports - Excellent.

Connected up the other TT configured as a Tracker and left it running for a while hoping to get spotted on aprs.fi but no luck.


Finally we seem to be having some luck with the TT, Simon contacted me as my TT had appeared on aprs.fi There are a few more things to adjust and understand, but I now have a TT setup as a TX tracker and another for RX display.


I installed the TT back into the car and drove about 8 miles. One position report was plotted on aprs.fi

I will need to enable the smart beaconing so it transmits more frequently when on the move, but it was great to see everything working. Currently the TT is using a 5 watt Kenwood HT and a half wave aerial mounted on the roof rails, it will be interesting to see the range.


Changed the TT settings to Wide1-1, Wide2-2

15/06/09 - Packet Radio Internet Gateway

Receive APRS packets and send them to APRS.fi

The tale of chasing down suitable Igate software is just to long and tedious to go into. All I wanted was a "simple" program to send APRS packets to APRS.fi to improve the coverage around Stevenage. All the software I found seemed to be old and/or unsupported. Static maps are all very well, but the Google map API does it so much better. Anyway in the end I found APRS4R which looked very promising.

APRS4R can be run on a re flashed ADSL router or a Linux PC. It is written in Ruby and provides the programs needed for Igate beacons, digipeating etc. It uses the goggle API to produce a local map if required. I decided to load it onto my Kubuntu PC.

TT4 Firmware Configuration

Downloaded the new firmware update program which certainly makes firmware updates easier.
Loaded the TT4 Alpha v0.54 firmware. This alpha version requires the configuration to be set by commands. There is no configuration program yet, as there is for the earlier versions.

APR4R Device Configuration

Mode - kiss/tnc2/tapr
Baud Rate - 19200

APR4R General Configuration

Beacon - Beacon plugin must be configured otherwise the Igate station will not appear on APRS.fi
Setup call sign
Serial port name
Setup station Long and Lat...
Introduction to Longitude and Latitude
Converting - Degrees, Minutes, Seconds to Degrees, Minutes and decimal seconds - Degrees, Minutes, Seconds (DMS)- Ok there is logic to that and I suppose decimal degrees (D.dd) can be justified. But Why, oh Why, do we need another format with decimal seconds? DM S.ss WHY oh WHY!

APRS4R must be restarted to activate any configuration changes.

17/06/09 - APRS4R on the EEEPC

Ubuntu Netbook Edition – An EEEPC had become available, so I acquired it with a plan of loading the APRS4R gateway software on to it. The USB stick boot seemed a good idea but I was getting SDC errors, which was slightly worrying!

It seems it did not like the USB stick very much. Tried another. Ah, there was a problem with the SD card, finally got the install running.

In the meantime we got the APRS tracker running in Simon’s car and one afternoon I followed him on APRS.FI down into London.

I mentioned my APRS experiments at the club and spoke to a few members about it, so I think there will soon be a few more stations on the air. I might even have a go at adding a tracker to my push bike - would be fun on longer rides.

Loaded EEEUbuntu onto the EEEPC following the install notes on aprs4r but I did need to "apt-get install ruby" as version 1.8 failed to run.

18/06/09 - APRS4R on the EEEPC

APRS4R - Configuration

As the EEEPC has no serial port I used a USB to serial adapter, which proved easier than expected.

Connect everything up

dmesg to find the device name ttyUSB0


Change rf0 device to /dev/ttyUSB0

Link Baud rate 19200

Mode kiss/tnc2/tapr

Packet Baud rate 1200

Saved the settings, ensured APR4R is started, rechecked the setting and then restarted APR4S for the changes to take effect

Monitored the Serial USB traffic with cat /dev/ttyUSB0

Control C to exit

Setup call sign, Long Lat etc

Saved the settings, rechecked the settings and then restarted APRS4R to make the changes

Reports received by the Igate started to appear on APRS.fi

24/08/09 - PMR, EEPC, APRS4R - Configuration

We had previously installed the APRS4R Igate at Simon's house, but unfortunately the handheld was just swamped by local pager interference/intermod. I do appreciate that a hand held on a colinear is not a recipe for selectivity, but it was all we had. Basically we need to use a better RX and perhaps a band pass / notch filter.

Neil (M0ARH) kindly loaned me a M294 PMR rig which he had previously modified for 144.800 packet. He was pleased that it would find a use again. Spent some time making up the required connecting leads etc, but received no packets. It will be used to replace the Kenwood on the M3NQG IGate. Using a £200 HT is really overkill.

25/08/09 - PMR, EEPC, APRS4R - Configuration

Triple checked the cables and finally received a couple of packets from G4ETG. The APRS4R EEEPC was not connected, so they did not get plotted on APRS.fi - Left it running.

26/08/09 - PMR, EEPC, APRS4R - Configuration

Still no plots on APRS.fi Proving tricky to test without a local APRS transmitter.


M1HOG - !5155.21N/00010.16W-APRS4R IGATE

M3NQG - !5155.38N/00010.93W-APRS4R IGATE

28/08/09 - Purchased a Kenwood TH-D7E APRS Handheld on Ebay.

I thought it would be great for /P operation and for testing.

18/10/09 - M3NQG IGATE

Still plagued by S7 to S9 RF interference on about 144.800 The PMR rig did pickup the odd local packet but that was about it.

So, last weekend I decided to make a considered and methodical effort to find the source. I had previously discussed this with Sean and Brian at the club, and they suggested that I hunt with a portable tunable rig.

I pressed the FT817 into service for this task. By tuning on LSB to the loud 144.800ish heterodyne then walking down the back garden and along the street in both directions it soon became clear that the interference was inside the house. I then moved to the front of the house and got roughly the same results, but the signal was a bit weaker. So, the offending signal was at the back of the house. I then moved into the house and pretty quickly located the source of the interference as the USB to serial adapter on the PC being used for the gateway... I guess the whole process only took 10 minutes - Tools for the job.

We did attempt to wrap the USB adapter in tinfoil, which gave some improvement. But the adapter had to go.

On Saturday we found another adapter which to my surprise Linux recognized right away and the FT817 showed as being much quieter! We plugged the PMR rig back in and sent it a few test packets from my D7 which it picked up OK. But it was not picking up much else. Outside the D7 had been picking up packets just using it's replacement whip antenna, so it looked like the PMR rig might be a bit deaf.

Back to the trusty F7E - Plugged everything back in and the packets started rolling in from all over the south east. After the struggles of the last few months it was great to see it working properly. Needless to say Simon and I celebrated with a cup of tea!

I do intend to have a look at the PMR rig and see if I can find out why it seems deaf. Next little project may be to use my FT857 and Simons FT7800 in our cars instead of the jury rigged handheld's. I have just got to have a think about the best way to organize it.

26/11/09 - Another Tiny Trak, Keyboard Adapters and a PYE MX294

Built two Byonics keyboard/display adapters, aided by a glass of Three Barrels Brandy. This adapter enables the LCD display and a PS/2 keyboard to be easily connected to a TT4 for configuration and use as a TNC. It seems strange to have a PS/2 keyboard connected to such a small device, but it works great.

25/12/09 - MX294 Interfacing

Interface Lead

W -> Pink/Red - PTT
E -> Blue - Earth
Y -> NC
R -> Grey - Audio In
B -> Yellow - Audio Out

Refitted the PTT and pre amp boards. Removed the in line din plug and socket from the PTT and audio connection cable and rewired directly onto the board. Made up another GPS lead - I am really getting the hang of that now.

Unfortunately during this work a purple wire came away from the board. The rig now transmitted on 144.700 - not ideal. After a Bishops Finger and some further investigation the wire was soldered back into the correct spot and 144.800 made a welcome return.

No plots on aprs.fi yet. It looks like the position is not being transmitted. Reloaded the older firmware - version 4.07 Basics now work. Not sure if it was a software or a lock/incomplete GPS fix issue. Left everything running for a few hours to see if the PTT was behaving correctly and if we could be "spotted". Only about 25% of the packets were received at M3NQG, but it is progress.

29/12/09 - MX294 Interfacing

Checked the Tiny Trak TX audio drive level. Turn for "maximum smoke", then back off a bit. The TT4 manual outlines how to do with using a scope, I think that may be a future task. Adjusted the drive level and now M3NQG is no longer hearing us - great.

Slightly puzzled I decided just to wind up the TX drive (RV4) to about 20 watts and fit everything in the car. It was at this moment I found the car battery was optically flat. A jump start and trip to Halfords later and everything was sorted. Upon our return we had a great track on aprs.fi - best DX 74 miles. Still no idea why it was not being heard earlier at M3NQG.

Reprogrammed the TT4 to TX every 30 seconds and only transmit valid positions. Repaired part of the MX 294 plastic front panel. The channel select fly lead and terminating plug is rather vulnerable, so I might just hard wire the channel select on the board.

31/12/09 - FT817ND, FT857, FT7800 Interface Cable

M1HOG-7 using the MX294 was spotted by various stations, but unfortunately M3NQG appears to be suffering from interference again, which will need to be investigated.

To add some flexiblity I investigated interfacing our other radios to the Tiny Trak. After some reasearch I came up with the following cable


FT 857 Data 6 Way Mini Din
TinyTrak Radio DB9 Male Jack
Data In - Red   1 Audio Out
SQL Status - Yellow   2 Carrier Detect
PTT In - Black   3 PTT Out
Data Out - White   5 Audio In
Ground - GND   6 Ground
    7 Power In


The Byonics cable also uses the RJ11/45 Mic connection, but I am not sure why it is needed, as my cable arrangement seems to at least transmit perfectly and is pretty simple - just set the frequency and packet mode on the rig then plug in - that is after I had soldered on the 6 way mini din. Although, even this task was eased by a glass of Admirals Ale

01/01/10 - FT817ND, FT857, FT7800 Interface Cable

Tested out the new cable with my FT 817 and it seems to work correctly on RX and TX, even picked up a few packets - as you do. Still need to optimise the TT audio RX and TX levels, but this simple cable should work great with the FT857 in the car and give 40 Watts APRS.

Still quite a bit of interference at M3NQG, although it was better with the FT817. Once again this highlighted the need for a more suitable receiver for the Igate.

02/01/10 - TT4 and FT857

Connected up the TT4 to the FT857 and power in the car. Set the FT857 for 144.800 PKT mode and away it went - Best DX 74 miles. This is a great interim solution, but ideally the TT4 would automatically switch to the packet freqency as required.

M3NQG is making up a similar lead for his FT7800 which will increase the range and free up his Kenwood HT.

04/01/10 - TT4 and MX294

MX 294
Channel select removed. Power LED being tested

Channel Select Fly Lead

Yellow, Orange, Red, Brown, Black, Grey - Connected
Purple, White - Connected

Removed the channel select fly lead and DB9 channel select plug. Cut back the cables and soldered them together to reselect 144.800. Hopefully no more problems with the channel select wiring breaking off the board.

Added an LED to replace the dead power lamp, but it hardly showed through the original lamp cover! Removed part of the cover, increased the current to the LED and carefully aligned it - MX294 with an amber power indicator.

16/01/10 - TT4, MX294, Kubuntu and APRS4R

Installed Kubuntu on an old Laptop to replace Simon's EEPC APRS4R Gateway. Nothing to report as Linux installs are now rarely a trial. Sound, network, screen drivers etc all just worked. Installed APRS4R and copied over my current gateway.yaml config file as a basis for this new APRS4R configuration.

Updated APRS4R and carefully checked the configuration. Beacons to APRS.fi correctly and picks up other APRS traffic from the internet, but does not pick up anything from the TT4.

[WARN] 2010-01-12 18:21:15 KISSSerialConnection:: readFrame: ex:
failed to allocate memory

Posted to the very helpful APRS4R group and was advised to increase the memory limit in /usr/bin/aprs4r I did this and the message no longer appeared, but still no traffic from the TT4

"cat /dev/ttyS0" shows packets arriving on the PC serial interface from the Tiny Trak. But no TNC RF packets are appearing in the APRS4R log or getting plotted on APRS.fi

However, I do get regular - [WARN] 2010-01-13 00:01:33 KISSSerialConnection:: readFrame: ex: execution expired - messages in the APRS4R log. Unsure of the significance of these I increased the AX25Socket timeout from 300 to 3000

Added the additional connections to complete the Null modem cable that connects the PC to the TT4 - just in case, but still no TNC packets show in the APRS4R log. Time to finish the Great Bustard.

Reviewed the configuration again - the TT4 is sending packet reports in TEXT mode not KISS.
Used " screen /dev/ttyS0 19200 vt100" to change the TT4 amode to KISS and then RF packets started to appear in the APRS4R log and on APRS.fi

17/01/10 - TT4, Kubuntu and APRS4R

Installed the new APRS4R Kubuntu laptop at Simon's. Seems to work well, although still some interference issues. Started up my M1HOG APRS4R Kubuntu PC.

27/06/10 - Updating the M3NGQ Kubuntu APRS4R

Updated the APRS4R Kubuntu distro to LTS 10.04, fixed a graphics card issue, by revising the Kernel startup options(!) Upgraded the APRS4R package, struggled with the WIFI (Intel) - in the end just manually started it once - ifconfig eth1 up - and thereafter it loaded automatically and ran fine. Updated the APRS4R Long and Lat for the new station location. APRS.fi now displays the Long and Lat, so no more converting one format of Long and Lat into another.

New location now displays correctly on APRS.fi

30/12/11 - M3NGQ Kubuntu APRS4R - Back in service

After having been out of service for a while the APRS4R Kubuntu laptop distro needed an update, well about 400. Did not take long though. Decided to use the MX294 with its new preamp (Thanks Keith - G4KGP) instead of the Kenwood HT. Wired it all up and it soon started plotting on aprs.fi
Installed at M3NQG. Working well.

05/01/12 - M1HOG Kenwood TH-D7

Remade the GPS and power leads. AA battery pack for GPS and Lipo for radio. Radio fails to pickup valid GPS. Checked the gps plug, the earth and ring are shorted out! Will need a new plug..

Tom Tom GPS lead - To Kenwood TH-D7

TX - Brown -> Ring
RX - Orange -> Tip
5V - Red -> Pin 4 TinyTrak GPS/Computer PIN
Ground -> Ground

06/01/12 - M1HOG-1 Kenwood TH-D7 - Back in service

Replaced the 2.5mm plug, all OK now. No idea how it happened, but these little plugs can short out. Certainly something to check in future!

07/01/12 - M1HOG-1 Kenwood TH-D7 - Cycle APRS

Lashed up the Kenwood, GPS and batteries in the cycle bag. Only using the HT antenna and it is low to the ground, but got a few plots. Just needs a better antenna. Configured mobile Tiny Traks are using TT version 4.07 iGate using TT Alpha .65


Make up a separate TT4 power lead to ease reprogramming - Done (29/12/09)
Test new lead with FT857 in the car - Done (02/01/10)
Remove the channel select fly lead on MX294 - Done (04/01/10)
Find a fixed audio output on the MX294 - Done
Power on LED indicator MX294 - Done (04/01/10)
Simon - Make up lead and test with FT7800 - Done (16/01/10)
Check MX294 output power
Build attenuator - Done (05/01/10)
Scope MX294 TX tones
Velcro to mount the GPS in the car
New SIRF 3 based serial GPS unit
Consider refitting the coax into the MX294 as the earth braid is splitting
Lipo pack, GPS battery, remake cables etc for Kenwood TH-D7 - Bike/Hike APRS? - Done (05/01/12)


Byonics - Suppliers of the Tiny Trak


APRS4R - K6DBG configuration notes

TinyTrak Wiki

TinyTrak Yahoo Group

TeraTerm Terminal Emulator

Null Modem cable with loop back handshaking

TinyTrak Kenwood TH-F7E Cable

APRS hardware options - Ready built, Kits and Build You Own