[Elecraft] K2 - Unstable power output on 40m (digital modes)

[Bob McGraw - K4TAX]

My take on this is baluns are baluns and common mode chokes are common 
mode chokes.  In many cases baluns do not provide adequate common mode 
choking requirements.  Thus both may be needed. Usually, the balun is 
located physically at the load and the common mode choke is located at 
the source.    In certain antenna configurations, a balun is used at the 
feed point along with a common mode choke and then a 2nd common mode 
choke at the source is required as well.

73
Bob, K4TAX
K3S s/n 10163
  

On 10/25/2015 10:09 AM, Brian - N5BCN via Elecraft wrote:
> Don,
>
> Yes, things settle down with a dummy load, so it looks like I'm dealing with
> RF feedback.
>
> Per the original post, I'm using an Elecraft BL2 balun at the
> coax/ladderline junction.  Shouldn't this act as the common mode choke that
> you suggest or are you suggesting to place a common mode choke in addition
> to the balun?
>
> Interesting idea regarding the KPA100 latest version since 40m is the
> troublesome band.  I purchased the KPA100 around 2011-2012, so I would think
> it has the latest hardware but I'll double check when I get a chance.
>
> 73 Brian, N5BCN