- Written by AC0VP AC0VP
Being new to APRS, I had a lot to learn. I started off with my old Yaesu FT-51R and started to go forward from there. I did some research and ended up picking up a TinyTrak4 and the TT4BT Bluetooth adapter. Pretty much figuring I wanted to avoid getting an external GPS unit and not wanting to have to carry a laptop around with me, I decided to go with aprsdroid loaded onto a Samsung Galaxy Tab 2.
The initial setup of the TT4 was pretty simple and interfacing it to the Yaesu FT-51R was painless. I have a Mobile mount in my truck for my Samsung Galaxy Tab 2, so I loaded up APRSDROID and set off to make this all work. The Cable from the TT4 to the FT-51R worked flawlessly, and besides putting the TT4 into KISS mode, there were no real configurations that I needed to do. The whole system worked flawlessly. Unfortunately, the internal Lithium battery in the Yaesu died and would no longer hold memories. So it was pretty much useless unless I wanted to re-program it every time I got into my truck.
Enter the Baofeng UV-5R+
So I decided to pick up a cheap chinese radio to see if I could replace my Yaesu with it for mobile APRS use. I picked one of these little monsters up off of Amazon for around $43. I also picked up a battery eliminator for it plus some accessories in case I ever wanted to actually use it as a regular handheld. I also picked up a HTKC interface cable from Byonics. After this all came in, I set out to repeat my initial configuration mobile again.
Issue #1.. After hooking everything up, I was able to transmit APRS data through the baofeng, but there was no discernible audio that could be heard in the packet transmission.
Issue #2. no packets were received by aprsdroid from the baofeng, I was monitoring on a second radio and I knew there was a lot of traffic. Thus began a lengthy troubleshooting process. I was able to resolve the transmit audio being low by going into terminal mode on the TT4 while hooked to the computer and doing a CALIBRATE. I increased the transmit level to 128 (As high as it would go) and tested again. I was finally able to hear the transmission tones and was able to receive them on another system. Fortunately that resolved issue #1.
Issue #2 was not so easily resolved, after looking at the cable that I received from Byonics and comparing it to the stock microphone, I noticed that the Microphone input jack had 3 connectors, while the interface cable only had 2 connectors. So I began a butchering job on my microphone cable and re-wired the connector to the TT4 interface cable to replace the cable I received from Byonics. I also sent a message to Byon about this, he has since replaced the interface cable HTKC with a Powerwerx cable HTK2C, so be sure you get this new interface cable instead of the old one. I have confirmed that it does indeed work and much better to have :) After doing the re-wiring job and creating my own cable, I did more testing and was able to send fine and receive intermittently if I had a really strong signal. The Baofeng does not have a good squelch on it, it is basically off or on, and even at a squelch setting of 1, it was hard to get packets to break the squelch unless they were really strong. Plus the baofeng has a receive delay in it that would delay breaking squelch for too long of a duration to actually be able to receive packets. So back into terminal mode on the TT4.</p>\r\n<p> </p>\r\n<p>In terminal mode, I had to set CDMODE TONE and CDLEVEL 10 initially. I also went into the Baofeng configuration and turned off the squelch tail Delay. 37 RPT-RL OFF. There is a great page for the settings on the Baofeng UV-5r+ at Miklor UV5R Page. If you need more information on the settings. Basically this allows me to leave the squelch wide open and still receive packets on the TT4 and relay them to APRSDROID on my tablet. I am still working on tweaking my CDLEVEL setting on the TT4, it is currently at 15 and seems to work relatrively well. The transmit works fine and I pick up tons of incoming traffic now for plotting and generally the system is extremely stable. Hopefully this information will help some of you that may be encountering difficulties with getting your Baofeng UV-5r and UV-5r+ to work in an APRS Application. Feel free to e-mail me at AC0VP at ARRL dot NET if you would like any assistance on this type of setup. It is a fairly inexpensive way to get APRS set up mobile if you are on a tight budget. Plus you can use your Android cellphone to do this also if you just want to report, the mapping is hard to see on a phone :)