I have one of these tuners that I use with my Omni VI (transmitter is almost
identical to Jupiter). It works FB for me, but I never tune at more than 25
watts even though the tuner is rated to 150 watts.
I think that it is just common sense to back down the power from 100 watts
before tuning up, just as it makes sense not to dump the clutch on your car
while you rev the engine. I usually tune at (and run at) 25 watts, which is
usually just enough to activate the tuner. I'm sure it is possible to fry
components in a manual tuner by tuning it at the maximum power, especially
if your antenna is horribly mismatched at that frequency. Why stress things
(your tuner, your finals, other hams on the band) unnecessarily? A good
tune at low power is a good tune at high power.
If you are seeing SWR increase (and not JUST reflected power, which WILL
increase as power increases if your SWR isn't 1:1), then you probably are
not in tune. Note that the AT11-MP will not AUTOMATICALLY tune if it has
found a setting that gives it an SWR of below 2:1, even if it can do better.
Hit the TUNE button again -- sometimes the tuner benefits from being tuned
twice, and will find a closer match. Remember that SWR is at the
intersection of the two needles, so as both move up due to increased power,
their intersection will move, but it should move parallel with the closest
SWR indicator on the meter face.
Note that, in my experience, the AT-11MP is not as good at tuning as is the
KAT2 autotuner built into the Elecraft K2 (I think the latter has a more
sophisticated tuning algorithm). Obviously, a human should be a better
tuner yet since we have a lot more processing power than a microprocessor (I
guess it depends on OUR programming). Note also that the KAT2 automatically
reduces power to no more than 3 watts during the tuning cycle, both to
protect itself and to protect the K2's finals. The KAT2 has the advantage
of having a microprocessor that communicates to that of the main rig, so
this can be done easily, while the AT11-MP doesn't.
Re LDG, I have found that they are a very good company to work with when it
comes to technical support matters, and they do understand their products.
Perhaps the tuner tries to cleverly take advantage of the fact that most
rigs reduce power when encountering bad SWRs, so perhaps a tuning/tuner
protection/rig protection strategy is to artificially increase the SWR to
the rig while tuning so that power is reduced to spare the tuner... and this
strategy doesn't work with the Ten-Tec rigs and thus the tuner is getting
more RF than it wants or can handle while it tunes. It sounds logical to
me.
Try tuning at the minimum power necessary to activate the tuner, try tuning
again if the first match isn't good, and see if these two strategies help
you.
- jgc
John Clifford KD7KGX
Heathkit HW-9 WARC/HFT-9/HM-9
Elecraft K2 #1678 /KSB2/KIO2/KBT2/KAT2/KNB2/KAF2/KPA100
Ten-Tec Omni VI/Opt1
email: kd7kgx@arrl.net
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