For those who would like to see an X-Lock-2 installation in a Ten Tec Corsair I
click on the link below
http://www.jessystems.com/X-Lock%20(rev%201).pdf
Basically the X-Lock is a refinement of what is called a Huff and Puff VFO
stabilizer. In operation the X-lock samples the PTO or VFO frequency at a
certain rate (which has some level of adjustment). A microcontroller is used to
manage the sampling and to store the set frequency. If during the course of the
sampling, the frequency is sensed as drifting a correction voltage is generated
that is supplied to a varactor diode. The magnitude of the voltage adjusts the
varactor so that more or less capacitance is effectively supplied to the tuned
circuit to compensate for the upward or downward drift. This happens so quickly
that the frequency appears to remain fairly static. The X-Lock 2 has additional
circuitry so that when a large excursion is sensed such as you would have when
you QSY, the correction circuitry is placed on "hold" for a short period of
time. No phase noise is introduced into the circuit for it is merely a
correction of frequency about a set frequency using a va
ractor diode.
Thus you get the idea of huffing and puffing. The X-lock in essence gives the
appearance of crystal stability.
In my Corsair I, prior to installation of the X-Lock 2, it took about 2 hours
for the Corsair to stop drifting. Now I can turn on the Corsair I and after
about a 2 second initialization it will stay on that frequency for hours on
end. I paid less than $40 delivered (depends on the daily exchange rate) and it
took about a day to build the circuit board and make the installation. Because
of the way I installed it there is some impact to the Corsair I RIT control. In
the wide RIT excursion the range is now about 3 kHz and was somewhat off
centered. I talked to Ten Tec and there is a pot on one of the boards that can
re-center the excursion so that an equal amount of offset is observed on either
side of the center position. That said I think you are stuck with a smaller
excursion range but it will be centered.
The X-Lock-3 just announced has added functionality beyond the X-Lock-2 for the
RIT.
73's
Pete N6QW (ex W6JFR)
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