[Elecraft] Re: Builder Alert #17; current metering

[Wayne Burdick]

Hi Rod,

The increase in C42 helps a lot with voltage/current reading stability. But as Larry East
discovered, a cap across R7 solves the specific problem of inaccurate 160-meter current
readings. They could be off by as much as 20% due to RF getting into the ISENSE line. I
doubt that this has caused anyone serious trouble, but we feel that it's worth it to add
the extra cap. 

73,
Wayne


WA9GQT@aol.com wrote:
> 
> Hi Wayne!
>       I am confused about this modification.  I did the original mod on an
> earlier posting about adding a 0.1uFcap between pins 4 & 8 of U3 on the
> control bd.  This would increase the C42 value.
>       I guess I need to add a 0.1uF across R7 on the control bd.  The other
> cap seems to have helped but I guess the one across R7 must help even more.
> Please explain. Thanks.
> 
> 73,
> 
> Rod WA9GQT  K2 # 1900