[Elecraft] Re: k3 SWR readings seem generous

[Stewart Baker]

On Sat, 3 Jan 2009 08:58:57 -0600, Phil & Debbie Salas wrote:
> "Hot switching RF in an external ATU is not to be recommended 
for
> any radio at any level."
>
> BUT - you DO hot-switch your K3's RF output when using any 
relay-based
> auto-tuner, including the internal K3 auto-tuner.  So my 
reasoning is that
> I'd rather hot-switch the 100-watt PA at 15 watts rather than 
the 10-watt PA
> at 5 watts.  And then, my MFJ-998 (which I use with my ALS-600) 
reads SWR
> more accurately at 15 watts than it does at 5 watts, so when I 
go to full
> power the tuned SWR is still minimum.  As Wayne stated earlier, 
SWR readings
> at low power may be less accurate due to the detector diode 
voltage drop at
> low power.
>
> Phil - AD5X
>
OK, to be strictly accurate......

"Hot switching RF in an external ATU (other than auto-tuners 
designed to be operated that way) is not to be recommended for
 any radio at any level."

I am sure that the *internal* K3 ATU has been designed to perform 
its tuning function at a safe power level, whatever output power 
level the operator selects.

Using the LP-100A I am avoiding (for the present) the influence 
detector diode volts drops vs power have on my SWR measurements.

Stewart G3RXQ

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