[Elecraft] KAT100 and external watt meter question

[Tom Hammond]

Glenn:

>I have a question as to what is the best way to use an external watt meter?
>I have a DAIWA CN-101L external watt meter. I originally had the K2100 RF
>out going to RF IN on the KAT 100 and ANT1 on the KAT100 going to connector
>labeled  TR  on the external watt meter and then the antenna connected to
>the connector labeled ANT on the external watt meter. I was getting a good
>match according to the K2100 display and the KAT100 LED's. The external watt
>meter however was showing high SWR on some bands especially 30 meters. On 40
>meters and 20 meters the external watt meter, KAT100 and K2100 SWR displays
>all agree. On other bands the external watt meter showed very high SWR. I am
>using a Carolina 40 Windom antenna by Radio works.

The KAT100 _ONLY_ changes the impedance of the load it's being presented 
between its ANT1 jack and the K2!!! Even though the ATU has done its job, 
by providing an acceptable SWR to the K2, it has NOT changed the load 
impedance of the antenna or its feedline.

As a result, the external wattmeter will always indicate the REAL SWR being 
presented to the KAT100, and the KAT100 will indicate the 'TUNED' SWR being 
presented to the K2.

>I re-arranged the configuration of the watt meter by connecting the RF out
>from the K2100 to the TR connector on the external watt meter. Then the ANT
>connector on the external watt meter goes to RF in on the KAT100. Then I
>connected the antenna to the ANT1 on the KAT100. I then went through the
>bands. The KAT100 re-adjusted the settings on all bands. Now the external
>watt meter shows matched power out readings compared to the K2100 display.
>The SWR is low on all the bands according to the external watt meter, KAT100
>and K2100. Is this the best way to have an external watt meter connected?

It all depends upon what it is you want the DIAWA meter to indicate.

If you want it to duplicate the reading of the KAT100, then you have it 
configured properly right now.

However, if you want to use the DIAWA to indicate actual SWR _ON_ the 
feedline going to the antenna, then you should put it on the OUTPUT of the 
KAT100, so it 'sees' what the antenna and feedline are doing.

73,

Tom  N0SS