Category Archives: VHF

A New APRS Gadget

I have had mixed results with APRS in the past. I had been trying to use an old Iphone as the GPS and TNC to feed a Baofeng radio. This seemed to be hit or miss most of the time and the phone is a bit clunky to carry around with the radio. I recently came across a listing on Ebay for “APRS 51TRACK X1C-2 Plug and Play For Radio with GPS +Battery” from China. The device acts as a small GPS enabled TNC that is plug & play with Baofeng HT radios.


I ordered one from Ebay and after about 2 weeks for shipping it arrived. The unit arrived with a cable setup for the Baofeng, a couple of spare RG-11 connectors, A USB to TTL board with a cable set. No manual or instructions were included. I contacted the seller in China and he promptly sent me the manual. It is in Chinese…


No worries as Google Translate did a fairly decent job of translating the text in the files. Charging the unit requires a Micro USB cable. Programming is a one time process that requires the unit to be dissasembled. This is easy enough to do by removing one of the end panels and pulling out the PCB inside. The Li Ion battery sits on top of the board with a small piece of foam in between. To program you will need to connect the USB to TTL board to the PCB using the included cable. Connect the USB board to a PC and it will install itself as a COM port. I struggled a bit with a terminal program (puTTY failed me this time) until i found that a freeware program called Termite did the trick. Once the port is opened (9600,8,1,N) press enter and the device will display its current configuration. Follow the instructions to change to your call sign as well as any other parameters  (SSID or WIDE-1 setting). Once configured, the cable can be removed and the box reassembled. Hook up the radio using the supplied coiled cable. Set the radio to 144.39 Mhz no tone and put it in VOX mode with the volume turned up. press the power button once to turn the APRS unit on. A red light will blink showing the state of the battery charge. The light will then blink blue indicating it is working on a GPS fix. Once the blue light turns solid it will start to beacon position data.

The unit performs as advertised once it is setup. here are the two manual files I receieved modified with English Translations :

APRS Track X1CF 20150501_BH4TDV

APRS Track X1CF 20150501_BH4TDV English

Overall the unit seems to work pretty well once configured and looks to be a decent value. I may add the optional temperature and pressure sensor to it next.



VHF Packet Winlink Working

Back in July,  I did some work to get packet winlink working over the local HF packet nodes. At the time, the local digipeter was not operating so I was not able to make a solid enough connection to exchange mail. The digipeter node is now operational here in Brownsville. I gave it a try after reviewing how I had done it before using the IC-7100 and a software soundcard modem. Quick review:

  1. CAT7200 software is installed and then run to create a com port that the IC-7100 will recognize for CAT control.
  2. UZ7HO Sound Modem software performs the TNC function via soundcard mode.
  3. RMS Express is run in packet winlink mode to exchange mail.

The radio is set manually to the digipeter frequency which in my case is 145.01 Mhz. An ultra important step is to set the mode to FM-D. Once all this was set I was successful in sending and receiving email at 1200 baud. Not bad for a soundcard mode.

VHF Winlink

I started looking into how to use VHF Winlink with the Icom 7100 and it’s built in sound card. I am close to getting this working. The Mail server nodes are all in the Harlingen Tx area about 30-40 miles from my QTH. The closest working digipeter is in La Feria, TX. Sadly, there does not appear to be a working digipeter in Brownsville. In order to get everything working you will need the following:

  1. CAT7200 software – This creates a virtual serial port that maps to the IC-7100 USB CV-I interface. Pretty handy software and should work for other older programs as well. Good overview of the setup can be found on WB4SON’s blog.
  2. UZ7HO SoundModem – This is a software TNC that connects to the virtual port created above and to the RMS Express software via TCP connection. W2YG has some good material on setup for Signalink hardware.
  3. RMS Express – I have used this before for HF email using WINMOR. For VHF at 1200 baud you will need to use packet winlink.

For setup info recommend seeing the video by K4REF showing an overview of the usage. I cannot report 100% success at this time. I am able to connect to the mail server and start handshaking with it. Unfortunately, no mail has been exchanged. I suspect that packets are being lost in the exchange resulting in retries and eventually it gives up. I’ll be playing with this some more and see if I can get a message through. Hard part is done with the rig and software setups.

IC-7100 now on VHF/UHF

It took long enough but I finally setup the IC-7100 for VHF/UHF use. The rig was programmed with the local repeater frequencies using RT-Systems programming software and a download from Repeater Book. Pretty straightforward overall. I should be able to use the IC-7100 on digital VHF nets run hear locally. There is a 6:30 net on Wednesdays through the repeater and a Simplex net on Thursdays at 7pm. I will still share the discone between this rig and the Yaesu FT-2900R.

One thing I noticed thus far is that he IC-7100 is hitting the repeaters in Harlingen and in South Padre Island. Not sure why this is but glad it seems to work.

Next up I’ll try and configure DStar.

Update on APRS

About a year ago I got APRS working with a Baofeng radio, a Easy Digi interface from N5CEY and a surplus iPhone running PocketPacket. I basically set it up, tested it and put it away.  In December, I put the APRS system back together and nothing seemed to work right. Over several days nothing but frustration. I decided to try this again this afternoon. This time I got it working the first time. Go figure. For future reference things are setup as follows:

Baofeng UV-5R:  VOX=1 volume up about halfway.

PocketPacket: Tracking ON, Report Altitude ON, TX interval 15 minutes, APRS-IS DISABLED, Audio Modem ENABLED, Transmit ENABLED, VOX trigger 500mS, Digipeater path Via 1 = Wide1-1; Via 2 = Wide 2-1.

Iphone volume full.

Next I will look for a way to strap the components together for portable use.

2m Tropo Ducting is On!

Tropo Ducting is on this morning (8:30am) in our area on 2m. Check it out:


Setup APRS Station

I finally broke down and bought a digital interface from Cliff, N5CEY that connects my Baofeng UV-5R to an iPhone. The iPhone is an older 4S model that is now retired after having been upgraded. It does not connect to a phone service but the WiFi and GPS work fine. I installed the Pocket Packet app and after a bit of fiddling with the radio and the app I started successfully sending APRS packets to the local digipeter.Mission accomplished as I now have a low cost dedicated APRS system to play with.

Worked the local VHF Digital Net

W8WKE runs a Wednesday night digital net at 6pm on our local repeater system. I had been wanting to try it for sometime but did not have an interface for my VHF rig. Clifford, N5CEY, hooked me up with one of his Easy Digi USB interfaces for my Yaesu FT-2900R rig. I set up Fldigi on my radio laptop and set it all up to the rig. The net uses MT63-2000L protocol. When the net started I was able to start decoding the transmission without any issues. Unfortunately, I could not transmit. The Interface handles the PTT with the rig and appears to the PC as a serial COM port. I had both DTR and RTS enabled but nothing worked. Then I noticed a small enable check box above the COM setting. I enabled it and the transmit started working without a hitch. I have played with HF modes on DM780 so I need to now learn Fldigi. When I get back from my next business trip I plan to hook up the VHF antenna to the IC-7100 and try and work it from there with HRD. Working this net was a lot of fun and I am looking forward to trying it again.

2m Tropospheric Ducting!

I finally experienced VHF tropospheric ducting tonight. I worked a station near San Antonio on simplex FM on 2m. I also heard and made contact with several stations in the upper valley that I had never been able to contact before. This was on 75W with my discone antenna up about 15ft. One of these days I need to get my 2m Moxon up to thirty feet and try it with the Yaesu at 75W.

A couple of new projects to think about…

I have been looking into making a custom air variable capacitor for an improved magnetic loop antenna. This looks like it would be entirely feasible and allow me to make a loop that could handle 100W. At 100W the voltage across the capacitor is just under 3.9kV at 14Mhz. The plate separation for this would be about 55-60mil. It would be a fairly large capacitor but it could be made fairly easily from sheet aluminum.

Just ordered a 2.5mm stereo plug to finish my wiring harness to connect my iPhone to my Baofeng HT to use with APRS. Been wanting to try Pocket Packet app for some time now and this will be my chance.

Also finished making an air choke for the 2m Moxon out of a coax patch cord. This is ready to test out with the new mast.