I have no idea how to cure a "zizzy," but I was told I had hum on my SSB signal after 6 years of perfect audio. Re-flowing the solder joints in the MH3 cured it. Whiskers, maybe. 73, Kent K9ZTV K3 s.n 021 On 2/22/2017 8:57 AM, ke9uw wrote: > Right forgot to say...this is on the 4K serial numbered K3 with all options > included. > > >