[Elecraft] K2 trouble on 160M

[Don Wilhelm]

Bill,

What does that K2 do when working into a dummy load?  If it still fails, 
the problem is definitely with the K2.  If it behaves, then you need to 
look at your antenna system - you may be better off with a 1:1 choke 
balun than your 4-1 balun.  I really don't know why hams persist in 
using a 4-1 balun when driving ladder wire feeders - the 450 ohms is 
only the characteristic impedance of the line and that says nothing 
about the feedpoint impedance - the ladder line acts as a transmission 
line transformer.  Measure the feedpoint impedance of the 450 ohm line 
with an antenna analyzer (operate it on batteries) where you connect the 
balun.  If the impedance is high, then use the 4-1 balun, but if it is 
low a 1-1 choke balun will be a better choice.  Which balun is better 
depends on the electrical length of your feedline.

The K2 can behave differently in the presence of RF-in-the-shack than 
your 706, so that is not a fair comparison.  Look at what you have 
connected to the K2 and ask what is different - the routing of the 
paddle cable?  How is the power supply cable routed? Do you have a 
microphone connected?  Have you grounded the microphone jack shell on 
that K2?

If you have a K2 problem, ask again with details of the failure with a 
dummy load.  Get it working with a dummy load before adding the extra 
element of the antenna into the problem.  All we can say right now is 
that your problem is either with the antenna, power supply, any cable 
attached to the K2 or the K3 itself.  Which one is pure guesswork until 
you reduce the number of variables.

73,
Don W3FPR

NZ0T wrote:
> Now that I have my K3 at home I moved my K2/100/KAT100 to our lake cabin. 
> Last weekend it started to shut down on 160 only when transmitting over
> about 70 watts.  All other bands are fine, the antenna (160M dipole fed with
> ladder line thru 4-1 balun and about 6' of coax into the cabin) is fine and
> the ground  seems fine.  It was shutting down the MFJ 4125 switching power
> supply so thinking maybe RF was getting into the supply I took the rig home
> and it worked just fine there.  Brought it back this weekend with an Astron
> linear supply and while that PS is not shutting down the rig still wants to. 
> I have used this same setup before here with no problems and this started
> happening suddenly last weekend.  I tried the rig without the KAT100 thru a
> manual tuner and it still wants to shut down.  My Icom 706 works fine on 160
> with the same configuration.
> Ideas?
>
> 73,
>
> Bill NZ0T
>   
>