[Johnson] Johnson VFO chirp

[Roy Morgan]

On Mar 7, 2014, at 10:58 AM, Larry Oneets <oneets123 at gmail.com> wrote:

> What can be done is to ground the capacitor C8 completely by removing the
> insulating washers from under it. As assembled it is only grounded by one
> wire.  Remove the insulating spacers from the capacitor and also the
> insulating washers on its shaft going to the front panel thru the metal
> shield.  Also make sure that the shaft going to the front panel is grounded
> properly. Clean the bearing where the shaft goes thru the front panel.
> This fix has been written up in several places and it does work for 40
> meter chirp.

All that sounds right.  AND, I remember one fix posted that the problem is RF getting into the VFO compartment via the VFO shaft.  The fix was to install a wiper on the VFO compartment that rubbed against the shaft where it enters the compartment - a direct grounding contact on the shaft.  Possibly a flexible braid soldered to the case and fastened to the shaft would work, too.

Roy

Roy Morgan
RoyMorgan at alum.mit.edu
K1LKY Since 1958