> That's interesting to hear because I don't get such fast QSK with my
> O II.
I just discovered that extremely fast QSK may *not* be a good thing whether
its from a Ten Tec or not. On the K3, there's a "QRQ" menu option that
allows for blistering fast QSK -- almost to the point where your own
sidetone becomes just another signal on the band.
This sounds like a good thing, right?
It is except under certain ionospheric conditions. For the past week, I've
been noticing audible, high intensity "clicks" after each keyed element
during the daytime on 40m CW. I thought I had a problem with my PIN-diode
switching system. But after scope measurements, nothing is wrong with my
set-up. Here were some of the conditions with QRQ mode engaged:
- Clicks heard much more at high power (1KW) than at 100W. Clicks gone
completely under 50W.
- Clicks noticeable on 40m, but only during the day. Weak echoes heard at
night on 40m. No other bands affected at any power level, nor other time
of day.
- Also, within the last month, my 80m dipole which is normally at a height
of 60 ft, is now at just under 40 ft while I make a new set of 600-ohm open
feeders.
See a pattern developing here?
The problem has been severe only recently, especially with the temporary
1/4-wave dipole height on 40m. The dipole at that height is producing a
take-off angle straight up at 90-degrees (i.e., NVIS). When the dipole was
up at its usual 60 ft height, the 90-degree lobe almost completely
disappears since the dipole is about 1/2-wave above the ground. Conditions
on 40m have been strange at night too as I'm hearing my echoes but not
clicks. However, as the band goes long in the evening, I think the NVIS path
disappears and some other ionospheric factor is responsible for the weak
echoes.
The F1 layer is roughly a 400-mile round trip, longer to/from F2. At the
speed of light, a 40m transmission launched at a 1/4 wave in height during
the day shoots straight up and is returned approximately 2 ms later in time,
perhaps double that time at night via only F2. The K3 has a super fast
switch time from Tx back to Rx. How much? I don't know yet, but I'm going
to measure it this week with a digital storage scope.
If I switch back to normal QSK which is still very fast (akin to TT), the
problem completely disappears day and night. The only explanation I can
offer is that in QRQ mode, the receiver is recovering within 2 ms after Tx
during the tail end of the ionospheric return. Perhaps only 1 ms of my own
signal is being heard, thus resulting in what sounds like a click and not a
tone during the day. But at night, I hear the tone as an echo when the band
goes long.
So, while I never would have believed one could have QSK that is too fast,
I've all but convinced myself that under the right conditions -- it can be
too fast. I'll know more about the Rx recovery time after my T/R
measurements this week.
Paul, W9AC
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