I'm reviving this thread to add another data point. My HTX-202, not
used for some time, is showing the "Er 1" error message. My owner's
manual, date code 10A1, makes no mention of this on page 36.

That's no problem, as I saw the link posted the last time this was a
thread at rrae. Thanks to all who posted with the solution to this
problem, and to WB3QCK for providing the website with the lavish
illustrations.

http://www.qsl.net/wb3gck/htx-202_err1.htm

Thanks again.