[Elecraft] KX3 - S/N 2917 - FW version MCU 2.18 & DSP 1.30!

[Mark via Elecraft]

Jim,


In support of Bob’s post requesting more information, let’s take this one step at a time:



Re:  “my KX3 has no Power Out with a "matched antenna".”  


It is not clear what you mean by a “matched antenna”, but based on your later statements, I assume you mean “matched” with your MFJ-993B auto tuner.  In my mind, that conflicts with the next statement:


“When I "match" the antenna There's power out…” 


That implies that after letting the MFJ tuner find a match, the KX3’s output is normal.  That is an expected outcome.


“…but when I switch to the antenna straight, there's nothing out.”



So is the antenna still “matched” when you switch to the “antenna straight”?  If so, how is it matched?  It sounds like you are saying that when you feed the antenna directly (not utilizing the MFJ auto tuner), you don’t get any power out of the KX3.  That is also an expected outcome IF your antenna length has not been adjusted to be resonant at, or near, the frequency you are using, or you don’t use feed line length matching.  I am reading between the lines here, but it appears this may be the case since you sometimes use the MFJ tuner.  (There is nothing wrong with using non-resonant antennas if you understand their use).


Assuming you do not have the KXAT3 Tuner installed (or it is disabled or bypassed), it sounds like the KX3 is protecting itself from a high SWR by folding its output power back.  In addition to non-resonant antennas, high SWR can also be caused by faulty feed lines, and many other causes.  A pretty inclusive list was posted on this list about a week ago.


As Bob mentioned in his post, more information would be helpful.  Detailed info about your setup when you get good output vs. your setup when you don’t get power out would be helpful.  I certainly understand that there is a tendency to panic and fire off a quick e-mail when things don’t work right (I've done it, too!), but the details are important and may save your KX3 a trip back to the factory for no reason, which is a waste of your time and theirs.


Mark

KE6BB