I replaced the cap at the emitter of Q90 with a 470pf instead of the 0.1nF. In the meanwhile I replaced the bifilar antenna wire with a short coax. Output power on 40 marginally diminished from 15 to 12.5w about. The power on higher bands marginally increased from nearly 2w to nearly 2.5w. But the 'instability' issue with full throttle noise on SSB on 10m has disappeared and I can also not attenuate the Vogad output. Overall I am happy with this one component replacement.
Il 01/mar/2019 08:40, "iz oos via Groups.Io" <and2oosiz2=
[email protected]> ha scritto:
Thanks for all the replies. According to the old schematics of my ver. 3 ubitx C81 should be 0.1nF, so I will see what changes with a 470pf as suggested by Farhan.
