[Elecraft] W2 Meter Question

[Don Wilhelm]

The wattmeter should be connected between the KPA500 and the KAT500 if 
you want to read a low SWR.  The SWR that is seen by the KPA500 is the 
only thing that matters, and that would normally be 1.5 or less.

Your connection (between the tuner and the antenna) will not change the 
SWR reading because you are reading the SWR into the antenna, and the 
tuner will not alter that.

The tuner will not change the SWR on the antenna, but it's function is 
to transform the antenna feedpoint impedance into something that will be 
seen as a low SWR by the transmitter PA stages - it does not change the 
SWR of the antenna/feedline itself.

If the SWR varies with the power level, that is usually a result of RF 
on the outside of the coax that can only be properly cured by common 
mode chokes placed in the antenna system.
See the RFI information presented by Jim Brown K9YC at 
http://audiosystemsgroup.com/RFI-Ham.pdf for ways to eliminate common 
mode current on the feedline as well as other problems with RFI 
suppression in the hamshack.

73,
Don W3FPR

On 6/4/2014 11:51 PM, K8JHR wrote:
> Greetings -
>
> I recently assembled and installed the W-2 SWR/wattmeter.
>
>
> Background:
>
> I have several antennas.  I have an A/B switch to select either a 
> vertical, or one of several dipoles further selected using a remote 
> coax switch.  The sensor is on the branch with the vertical.  I use a 
> linear amp at 500 watts when net control for a Brand X rig owners' net.
>
>
> Question/Problem:
>
> When using the vertical, the meter works on the A side of the switch 
> works properly.  But, using any of dipoles, on the B side of the 
> switch, it goes crazy and all the diodes light up.  It only does this 
> when the amp is on line.  I tried re-routing the sensor cable with no 
> advantage.
>
> Any ideas?   Thanks in advance.
>