[Elecraft] OT a bit: K3 Ant Tuner

[Wes]

Good points, some of which I considered making in my last post.  Regarding the 
SWR measurement capabilities of the K3 (or many other devices) I wrote about 
this too in another thread:

http://elecraft.365791.n2.nabble.com/K3-SWR-Numerical-Indication-td7643839.html

Wes  N7WS


On 7/5/2019 10:37 AM, David Gilbert wrote:
>
> It's not just a power issue.  A filter only achieves its design goals if the 
> impedance feeding it and the load impedance it sees are as expected.  Most 
> filters are going to want to be fed by 50 ohms and see a load of 50 ohms.  
> Most rigs (not sure about the K3) don't actually present a pure 50 ohm output 
> impedance, so using the internal tuner in the K3 supposedly would assure that 
> the filter sees the correct feed impedance, and for an operation like Field 
> Day having a properly performing filter might be more important than a bit of 
> power loss in the K3 tuner inductor.
>
> On the other hand, I'm not sure that the SWR meter in the K3 is a perfect 
> indicator of a match to a 50 ohm load.  I recently did some SWR measurements 
> on a new antenna setup for five different bands (three different antennas) 
> using four different indicators ... the SWR meter in the K3, an AEA HF-CIA, an 
> Elecraft W2, and a new FA-VA5.  All four instruments were located in the same 
> spot on the transmission line for each band (I swapped them in and out), and I 
> plotted the SWR curves for frequencies across each band band.  The readings 
> with the most deviation from the others came from the K3, and for certain 
> cable lengths (I did readings with and without an additional 7 foot length of 
> feedline inserted) it was significant.
>
> 73,
> Dave  AB7E
>