KPA-1500 issues

Posted by ANDY DURBIN on Nov 29, 2018; 10:42pm
URL: http://elecraft.85.s1.nabble.com/KPA-1500-issues-tp7646571p7646647.html


"In addition the tuner may not always be in the segment you think it is. This is due to the 8KHz resolution of the internal counter, that wins over you sending it a more accurate frequency, and also the hysteresis algorithm that can require a 2 segment frequency change before the tuner changes. Gary from Elecraft says "if you are off by one bin segment then it should not matter too much"


I have the same frustration with my KAT500 tuner. I send it a frequency with 1 kHz resolution ( I was using 1 Hz resolution but found that was futile) but it wants to override that frequency with a much less accurate RF derived  frequency.  I suggested to Elecraft that the frequency received over the serial interface should have priority unless the RF detected frequency differed by more that a user set threshold.  That proposal was rejected on the basis that here cannot be two master frequency sources. That argument was lost on me since I have worked in the development of avionics systems where master swaps are common and dynamic data source selection is also common.  

I settled for sending my KAT500 a new frequency any time the actual transmitted frequency differs from the KAT500 reported frequency by more than 8 kHz.  I have also  tweaked FCCS and FCMD (not easy because they don't seem to work as documented) to make is less likely that RF detected frequency will usurp my serial data frequency at least for CW transmissions.

I spent a fair bit of time manually selecting  L and C to get a near perfect match in the band segments I use.   I find it frustrating that the KAT500 firmware thinks it can do better than what I tell it to do.

I wish Elecraft would give serial data frequency priority over RF detected frequency until a difference threshold is exceed.  It would not be difficult to do.

Andy, k3wyc




   
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