quarter Wave Stubs

[ei7cd]

I am not able to calculate quarter wave stubs with my AIM4170B. When I enter the frequency for the stub and the starting physical line length and hit enter I get a message 'finding velocity factor please wait' I then get a message 'AIM684a.exe has encountered a problem and needs to close' the red RUN light stays on. The analyser is running from a 12 volt battery with plenty of capacity and will carry out other measerements, for example 'Distance to a Fault' which could be used to cut stubs but not as effectively as the quarter wave function. This seems to be a recent fault Help would be appreciated.

EI7CD

[w8dq]

I had that same problem a 40m 1/4 with version 685, the same exact thing. Now if I was working on a higher freq stub like a 2M it was OK. I down graded to Version 680 and all is well.