[Elecraft] K1 KAT1 SWR Adjustment

[Don Wilhelm]

Carl,

The main reason for the reflected circuitry in the KAT1 is to monitor 
for the lowest SWR during a TUNE operation.  For that purpose, it is not 
necessary that the indication is accurate.

If you wish to calibrate the SWR indication, check the C9 balance 
setting first - connect a known good 50 ohm non-reactive load (the 
Elecraft DL1 is good)  If you do not know for certain about your dummy 
load, measure it with an antenna analyzer.  If it is anything other than 
a pure 50 ohms resistive, you may still achieve a null, but the bridge 
will be balanced at the impedance of your actual load and not 
necessarily 50 ohms resistive.
Next, calibrate the forward power, and lastly, calibrate the SWR 
indication (by adjusting only the trimpot) using a resistive load which 
produces a known SWR, such as a 100 ohm (SWR=2.0) or a 75 ohm load 
(SWR=1.5).

The power level is not critical to any of these adjustments, but it may 
be easier to see the null at 5 watts than at 1.5 watts.  If you want to 
do it at 5 watts, adjust first at lower power and then make quick, but 
small, adjustments at the higher power.

73,
Don W3FPR

Strode, Carl R wrote:
> My new K1 is working great!
>
> However, the SWR indications appear to be a bit low.
>
> For example, I have a ground mounted vertical antenna (Hy-Gain 18-HT Hy-Tower) with lots of radials.  The SWR as indicated by the K1 is 1.0:1, which does not appear to be correct.  My trusty MFJ 249 tells me the SWR on this antenna is closer to 1.5:1, as I would expect.
>
> If I connect a non-inductive dummy load of 100 or 25 ohms, the indicated SWR is closer to 1.5:1 instead of the expected 2.0:1.
>
> When adjusting C9 for the lowest possible voltage, the instructions tell me to set the power out to 5.0 watts, however the manual does not tell me to increase power from the 1.5 watts nominal tuning output level to the full 5.0 watts.
>
> Should I enter TUNE mode, then tap to increase output power to 5.0 watts as I make the C9 adjustment?
>
>
>