[Elecraft] KAT100 Tuning Failure

[Don Wilhelm]

Since you have the KPA100 disconnected and the KAT100 connected to the 
KIO2 for control, the KAT100 with the K2 ATA menu in CAL, you can 
calibrate the KAT100 much like the KAT2 for wattmeter balance and 
forward power.

Connect the K2 to the RF IN and a dummy load and inline wattmeter to ANT1.
Set the power to 8 or 10 watts, and do a TUNE.
Measure the voltage at U5 pin 5 and adjust C1 to achieve a minimum 
voltage - it should be close to zero volts.
Then set R3 (forward trimmer pot) so the K2 display agrees with the 
power indicated on the external wattmeter.

Since you do not have 25 ohm or 100 ohm dummy loads, power off the K2 
and measure the resistance from U5 pin 3 to ground.  Then multiply that 
resistance by 1.2 (remember that value).
Then measure the resistance between U5 pin 3 to ground and adjust R4 to 
produce the resistance value you calculated.

It does sound like you have things adjusted close to optimum, but a 
double check will do no harm.

If you do find another dummy load to create a 25 ohm dully load, you can 
touch up the R4 (REFL) trimmer pot to properly indicate an SWR of 2.0.
If by that time you have the KPA100 inline, you still can do it with the 
KPA100 "on it's back" to the right of the EC2 enclosure (supported on a 
boox or box about half the height of the enclosure).  If you do it with 
the KPA100 inline, adjust R4 so the KAT100 LEDs indicate an SWR of 2.0 
and ignore the K2 display.  With the KPA100 inline, the K2 display will 
show the power and SWR seen by the KPA100 wattmeter, not the KAT100.

73,
Don W3FPR

On 8/10/2015 8:25 PM, JeremyJones wrote:
> Thanks Don.  The KPA 100 is still disconnected.  I have the base K2 with KAT2
> connected to the KAT100 in the EC2 chassis.  This normally has the KPA100 on
> top, but was removed as suggested to perform the troubleshooting.
>
> I don't have an extra dummy load at this time, but I am going to see if I
> can borrow one and test as you suggested.
>
>