Hi Andrea,
As the designer of the KX1 and options I thought I'd chip in here.
1) my G5RV, accidentally shortened because of a wind gust, cannot be
tuned by my IC-736 in 30m while the KXAT1 happily reports a perfect
match (r1.0). Is that plausible?
Tuners in some commercial transceivers are limited either by power
handling or by firmware to 3:1. The KXAT1 is quite capable of matching
some (but not all) loads that are 10:1 or higher, thanks to the low
power of the KX1.
2) in order to debug the problem above, how can I force the ATU to
forget the 30m band LC settings and retune, possibly without
resetting the main cpu? If I force a retune in 20m and 40m I hear lot
of relays clicking, while all is quiet on 30m. I checked the error
code and it is E00, so I'm stuck.
Just tune up into a dummy load on any band you want to reset.
3) the pwr meter of the ATU reports 5.2-5.5W on 30m as opposed to
3.0-3.3W on 40m and 3.5-3.8W on 20m. No accurate calibration was done,
but the difference is striking. Any clues/things to investigate?
If this happens even on a dummy load, the rig probably really is
putting out higher power on 30 m. The knee in the low-pass filter
moves around a bit and can have a large effect on per-band efficiency.
The knee can be adjusted to equalize the bands somewhat by squeezing or
spreading the low-pass filter toroid windings.
As a side-note (pun not intended), with respect to the KX1 power mods
suggested a while ago, I have a question: has anyone thought about
putting a fuse on the battery line? The potential for damage due to a
shorted Q6 is quite relevant even when running off internal batteries;
my external power cord is fused and this has already saved me once 8-)
In general I recommend operating the KX1 at 4 W and lower. The extra dB
or two you get by exceeding this is usually not worth the risk.
As for fusing, I don't know of any cases of battery melt-down on the
KX1. Remember that the maximum power output when running from the
internal battery is about 2 watts. If you really wanted to fuse it, you
could use a very small self-resetting polyfuse -- see www.digikey.com
for possible types to use. The main problem in the KX1 is space, so
you'll need a *really* small fuse.
73,
Wayne
N6KR
---
http://www.elecraft.com
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