[Elecraft] KAT100 and external watt meter question

[Tom Hammond]

Mac:

>After adjusting it with a dummy load per the instructions, I proceeded to
>hook it up to the G5RV with a Diamond SWR bridge in line (about 3 feet) from
>the K1 output.
>
>The tuner did not want to tune the antenna on any band properly and the
>output power was lower than normal while the SWR on the external wattmeter
>read way high.
>
>After playing with this for a half hour, I called Scott at Elecraft and
>expressed my dismay.
>
>Once he found out about the external wattmeter in line the problem was
>solved.  You simply cannot get proper operation from the tuner with that
>thing in there.
>
>As soon as I removed it, the tuner brought the SWR down to normal, usually
>1.0 and even 1.5 on 30 meters. Everything back to normal.

Though you noticed the difference, I somewhat doubt that it was due to the 
external bridge, but rather the fact that you changed your feedline length 
by 3' of coax. Try putting the coax BACK in the line, but use a 
double-female adapter in place of the external bridge. Chances are your 
tuning problem will return.

I say this because I've run external SWR bridges in-line for decades with 
no problems whatsoever... still do to this day. BUT I have, in the past, 
found that if there's an appreciable SWR on the feedline coming into the 
shack, the length of the feedline CAN change to point at which you're 
looking' at the load, and it can sometimes cause tuning problems for 
transmatches. Changing the length of the feedline changes the point (along 
the line) where you look at the load and can make tuning easier.

Of course, adding/removing line length does NOT change the SWR, on the 
line, just the point at which you (or the ATU) look at it.

73,

Tom  N0SS