[VHFcontesting] FT-726R Problem

[David Tanks]

I have a friend that has this radio from the 80's-90's era. It works fine on 2 meter SSB and FM; on 6 meter SSB and FM it has developed what sounds like a high-pitched tone when the radio is keyed. The Tone switch is off, and has been quickly turned on and off to clear up any dust/dirt that might have gotten in there, with no improvement shown. Has anyone else run into this problem, and how did you fix it? Thanks in advance!

David AD4TJ