Re: KPA-1500 issues
Posted by
ANDY DURBIN on
Nov 29, 2018; 11:51pm
URL: http://elecraft.85.s1.nabble.com/KPA-1500-issues-tp7646571p7646649.html
"There is also a limit to how far the firmware will go to reducing SWR. In the interest of minimizing tuning time (and relay wear and tear). If the match is less than 1.3:1 or so, tuning will be declared adequate and will be stopped. Since the typical driving transceiver can tolerate an SWR of at least 2:1 without power foldback or damage, setting that 1.3:1 limit is reasonable - unless you are a 'purest' and mentally can only tolerate a 1:1 SWR (big grin)."
I have no interest in how good any Elecraft tuner is at finding a minimum SWR solution. I use my LP-100A which will give good complex load readings with far lower power output that is required for the KAT500 to give a much less useful SWR reading. None of my tuning solutions was derived by the KAT500. It can't find a solution with the 5 W signal I like to tune with.
As to your assertion that an SWR of 2:1 should be tolerable I call "bollocks!" The KPA500 will not even accept 1.5:1 if the R is on the low side of 50 ohm. SWR is a poor indicator of the load presented to an amplifier. I was perfectly happy with an SWR of 1.5:1 until I started using my KPA500 and realized the very significant difference the complex load made to PA dissipation and the probability of fault trips.
I use my KAT500 as a manual tuner and just wish it would do what I tell it. (I found a solution for this frequency, I gave it the frequency, use the solution I told it to use for that frequency.)
Andy k3wyc
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