[Elecraft] KX3 antenna tuner intermittent operation

[Dave KW4M]

I experienced a related issue with the KX2 ATU during the CQ WW contest this
weekend.

After a frequency change during search-and-pounce, I would send my call,
KW4M.  What was actually transmitted was KM4M.  The first dit in the second
letter was chopped off.  I could hear what sounded like a relay click when
this happened.

This happened on multiple occasions.  Subsequent transmissions were fine
until another significant QSY.

The CW keying was computer-generated at 25 WPM.

-Dave


KW4M
wayne burdick wrote
> Ralf,
> 
> Like the K3's ATU, the KX3's ATU stores up to 32 segments of LC data on
> each band. On 160 m the segments are 10 kHz wide (1800-1810, 1810-1820,
> etc.). Anytime you move the VFO into a new segment, then transmit, the ATU
> will reload the last-used LC data for that segment (or the closest segment
> for which data has been stored). If the data is the same as for the
> previous segment, nothing will change. If it's different, the LC data will
> be sent to the ATU's relays, and the "ATU" icon will flash. 
> 
> Note that this will not happen until after you pause 1/2 second in your
> transmission. This way we don't mess up the timing on your first
> transmission if you were in CW mode.
> 
> My guess is that you moved the VFO into a new segment where you had
> previously tuned up into a different load, so that the LC data was a
> little different. 
> 
> There are a couple of things you might want to do. If you changed
> antennas, you can optionally go into the ATU MD menu entry and hold CLR to
> erase all of the ATU LC data for the current band. Then retune the ATU in
> the part of the band you use, as needed (when SWR is high). 
> 
> A more exhaustive approach might be useful if the antenna's SWR varies
> widely across the band (often the case on 160 m): Tune up the ATU ahead of
> time on every segment. That is, set the VFO to about 1805, tune the ATU,
> then move to 1815 and tune the ATU, etc. This is usually overkill, but it
> would optimize the LC settings ahead of time for a narrowband antenna.
> 
> You might try the above and let me know what happens.
> 
> Another possibility is that you simply have very high SWR resulting in
> RFI. If that were the case, reducing power to a couple of watts would
> reduce RFI and the symptoms would go away (or at least be different). My
> guess is that this is not what's happening; you're just seeing the ATU
> retune in new segments.
> 
> I'll also send you our latest field-test firmware which is likely to be
> released as beta later today (rev 1.47). It has significant stability
> improvements that could have some bearing on ATU-related problems.
> 
> 73,
> Wayne
> N6KR
> 
> 
> On May 2, 2013, at 1:16 AM, DL6OAP <

> Ralf@

> > wrote:
> 
>> Hi, 
>> 
>> I received my KX3 one week ago and had some fun yesterday with it and an
>> end-fed wire antenna roughly 20 mtrs long. The ATU worked great on
>> getting
>> the SWR down to 1:1 (not on 160) but there was an issue that concerns me:
>> while transmitting, the ATU icon in the display went flashing and the SWR
>> changed….
> 
> 
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-----
Dave
My Web Site 
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