Vertex VX-4000V

Notes about converting a Vertex VX-4000V to use on the ham bands

I picked up a Vertex VX-4000V from ebay for about $40. It did not come with a microphone, but my goal is to use the radio for packet radio. By default it has a frequency range of 148-174MHz. There are some resources online about converting them to use in the ham bands. It sounded much easier than it actually is....

Connecting to the Radio

I could have purchased a programming cable for $30, but I decided to try to be cheap and build my own. I started with designing a breakout board in KiCAD to go to standard pin headers from the radios proprietary connector. It uses spring-loaded pins to make contact with the pads on the radio. The other side has two rows of standard 0.1" pins to connect to jumper cables or another breakout board.

My initial attempts at using the breakout board along with a USB to TRRS programming cable for a Yaesu VX-5R did not work.

At this point I ended up just purchasing a programming cable from KJ6ZWL, BlueMax49ers, on ebay.

Programming the Radio

Using the cable and CE49 v5.17 programming software I was able to successfully program the radio. The software needs to run on Windows XP so I setup a virtual machine to run XP. The radio is set up to transmit and receive from 148MHz to 170MHz. To get this into the 2M ham band, a hex file needs to be edited.

To get the radio in PC programming mode, press and hold the button under the power button while you turn on the radio. The screen will say "PC Clone".

I first programmed the radio in its initial range to make sure everything worked. I programmed in the NWS weather radio frequencies to verify receive worked. Receive worked well, but the audio was a low.

I next edited the hex file. I used HxD to edit the file. I found 0x08D24D00, 148.000.000 (the lower limit) in the hex file, and replaced it with 0x08954400, 144,000,000 (the new lower limit)

When I opened the modified file in CE49 I was able to input frequencies down to 144MHz. I was also able to program the radio with these new frequencies. I programmed in some local repeaters and tested. It works!!!

Next steps is to figure out why the audio is so low and to test transmit.

One of the screws holding the top cover on was stripped. I drilled out the screw and was able to open the radio. It seems some modifications were done to this radio, and there was an accessory card installed! I took out the accessory card and there was unfortunately very little identifying information. I looked through the brochure of the radio from Vertex and was able to identify the card as the MDC-1200 card on the FIF-7 interface board. The MDC-1200 is an ANI encoder for the MDC-1200 Standard by Motorola. It allows data to be sent over the voice channel. My guess is the audio level is low due to the board not being set-up correctly. I don't need any of the features of the accessory card so I removed it. Turning the radio back on, the audio level is very loud and clear.

Testing Transmit

To test transmit I used a few jumper cables along with the breakout board I built before. I attached the radio to a dummy load and using the jumper cables shorted the PTT pin to GND. It started transmitting!!!

Then stopped....

I blew the 5 amp fuses I had on the power supply. I threw in 10 amp fuses and tried again. It works! I don't have a microphone or any input to test with, but it breaks the squelch on my handheld!

When working to get the radio working with packet, I initially had some issues getting transmit audio to work. I could key the radio, but wouldn't get any audio out. It turns out the radio had been modified, as seen in some of the above photos. The orange wire running across the board is not stock. I cut the wire as well as removing an extra resistor that was added across two of the accessory pins. While the radio was open I also adjusted a solder jumper to set the accessory port to support 9600 baud input and output. Changing the jumper removes the audio filtering from the signal path, allowing faster data speeds.