I have performed this modification to my own VX-170, which I purchased in Dec 2005. I can testify that it does, in fact, work and work quite well.
However, using Amateur Radio equipment to transmit in frequency bands that said equipment is not FCC type accepted for is illegal.
I am not accountable or liable for what you do on your own to your own equipment. Use this information at your own risk. No warranty or guarantee is implied or given.
This modification does not affect the use of computer programming software from RT Systems or G4HFQ. Thanks to Bryce K1GAX, for the info on G4HFQ's 2070 VX-170 software. I hadn't tested it until he e-mailed me and said it worked on his VX-170.
VX-120 & VX-170 Product Brochure from Yaesu. (.PDF file)
Click on Picture for the Supersized Version.
1) Remove the battery from your VX-170.
2) Remove the Black Adhesive Cover over the FTD-7 Paging Unit installation point. It is located directly below the serial number barcode label, parallel to the FCC warning label. It looks like part of the case, but you can see the border of it. Just gently peel it back. It comes up quite easily.
3) Find the zero ohm resistor midway between the two connectors near the rectangular opening in the circuit board. (refer to the picture.) Supposedly there are radios that have two almost right next to each other. (Mine had one, but looked like it had two at one point.)
4) Remove the zero ohm resistor. (Or both resistors if you have both) Use a low wattage soldering iron, or carefully pinch off with mini needle-nose pliers. Another option my brother, Jerry N9XMX , suggested was to remove about 1 mm of the trace on one side of the resistor. That way if you want to restore the radio to non-extended mode, you can solder it closed again.
5) Replace the Black Adhesive Cover and the battery.
6) Now, my radio reset itself when it powered up. I did not need steps 7 or 8. Bryce K1GAX states that his VX-170 reset itself without steps 7 & 8 as well. However, you may find it necessary to follow these additional steps;
7) Press and hold the Monitor/Lamp switch and turn on the radio. (The radio will show SETRST on the display.)
8) Rotate the dial knob to ALLRST and press F.
Your radio is now modified to transmit on MARS/CAP frequencies, IF YOU HAVE THE NECESSARY PAPERWORK TO ALLOW YOU TO TRANSMIT ON MARS/CAP FREQUENCIES. However, this is NOT, repeat NOT, legal for MURS, Business Band, or Public Service frequencies. The FCC can fine you and seize your radio(s).
© 2007 www.Cato2000.com All Rights Reserved