[Elecraft] (no subject)
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[Elecraft] KAT2: SWR Accuracy
I've just completed alignement of my KAT2 and am a bit dismayed by its SWR accuracy. I feel pretty confident that I found the true dip in C55 at a value of 12. I then aligned the forward power (R1) using an OHR WM-2 that was aligned on 40m against test equipment. The 50 Ohm dummy load I'm using reads a flat 1.0:1 up into the 2m region on an MFJ-259B. I'm fairly happy with the forward calibration which yielded the following results: BAND K2WM-2 160 4.4 5.0 804.6 5.0 404.9 5.0 305.2 5.0 204.9 4.9 175.0 5.0 155.1 4.9 125.5 5.0 105.6 5.0 I initially calibrated reflected power (R2) by measuring the wiper-to-ground resistance on R1 and setting R2 for the same wiper-go-ground resistance. The reflected calibration results range from 1.0:1 on 160m to 1.2:1 on 10m into the 50 Ohm dummy load. However, the SWR readings I see when using a 25 Ohm dummy load (confirmed on MFJ-259B) aren't very good. The KAT2's 25 Ohm dummy load readings range from 1.7:1 on 160m to 1.2:1 on 10m. Given the preceding results, I decided to set the reflected adjustment (R2) to show 2.0:1 on 40m into the 25 Ohm dummy load. This time, the results varied from 2.1:1 on 160m to 1.3:1 on 10m. I have considered going back and readjusting R2 to show an average reading of 2.0:1 across the bands into the 25 Ohm load (higher than 2.0:1 on 160m, lower than 2.0:1 on 10m -- a compromise). Is the accuracy displayed above typical of the KAT2? If not, maybe I need to go back and reevaluate my C55 calibration (although I felt pretty confident that it is correct). Thanks, Michael N9BDF, K2 #4137 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] K2: Temperature of driver Q6 during keydown
Fine tuning of the PLL temperature compensation circuit requires transmit cycles of 15 minutes or so at 10 Watts. However, I've found that driver Q6 gets hot to the touch after just a few minutes of key-down. Is a transmit cycle of 15 minutes really a good idea? Thanks, Michael N9BDF, K2 #4137 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] KAT2: Can't Get Bridge Null Adjustment (C55) Below 012 mV
I'm performing the Bridge Null Adjustment (C55) on my KAT2, but can't get it below 012. It is clear when adjusting C55 that I _AM_ centered in the middle of a dip. However, I can only get the value to go down to 012. Per the manual, I've checked T1's windings and their continuity and have checked the continuity and arrangement of the cable wires (J7 and J8) -- I don't see any problems. Is a minimum value of 012 good enough, or do I need to look more closely at the SWR bridge components? How might the operation of the KAT2 be affected by this higher than normal value? Thanks, Michael N9BDF K2 #4137 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
